HIGH FARMING WITHOUT MANURE. 



SIX 



8 

.Via 

LECTURES Otf AGRICULTURE, 



DELIVERED AT THE EXPERIMENTAL FARM 
AT VINCENNES. 






I 



M. GEORGE VILLE, 

PROFESSOR OF VEGETABLE PHYSIOLOGY AT THE MUSEUM OF NATURAL 



HISTORY, PARIS. 



« 



BOSTON : 

PRESS OF GEO. C. RAND & AVERY. 
1866. 



9 



\2LmmzM 




Class £l_ 

Book 



.h-L 



J *" 



♦7 

HIGH FARMING WITHOUT MANURE. 



SIX 

LECTURES 0i\ AGRICULTURE, 



DELIVERED AT THE EXPERIMENTAL FARM 
AT VINCENNES. 



M. GEORGE VILLE, 

PROFESSOR OF VEGETABLE PHYSIOLOGY AT THE MUSEUM OF NATURAL 
HISTORY, PARIS. 



BOSTON : 

PRESS OF GEO. C. RAND & AVERY. 
1866. 



^ 



m EXCHANGE 

Mr3 l 06 



CONTENTS. 



LECTURE FIRST. 

(5th June, 18C4.) Pagk 
On the Science of Vegetable Production 2 

LECTURE SECOND. 

(12th June, 18G4.) 

On the Assimilation of Carbon, Hydrogen, and Oxygen 

by Plants 18 

LECTURE THIRD. 

(19th June, 1864.) 

On the Mechanical and the Assimilable Elements of 

the Soil " 32 

LECTURE FOURTH. 

(26th June, 1864.) 

On the Analysis of the Soil by Systematic Experiments 

in Cultivation 40 

LECTURE FIFTH. 

(3d July, 1864.) 
On the Sources of the Agents of Vegetable Produc- 
tions 66 



IV CONTEXTS. 

LECTURE SIXTH. 

(10th July, 1864.) Page 

On the Substitution of Chemical Fertilizers for Farm- 



Yard Manure 



Appendix 106 



TRANSLATOR'S PREFACE. 



The researches of M. Ville, which are now 
placed at the head of the most important discover- 
ies science has yet made for the benefit of agricul- 
ture, were, like all innovations, received at first 
with something more than coldness and indiffer- 
ence. It has ever been thus : the most pregnant 
ideas, those destined to exercise the happiest in- 
fluences upon society, are always accepted with 
reluctance ; for they disturb preconceived no- 
tions, they upset so many plausible theories, and 
humble our conceit ; therefore they are always 
met with objections and opposition from your 
" practical men " alarmed at the scientific rigor 
of the formula, and from savants always disposed 
to oppose one theory by another. But true sci- 
ence ultimately makes its way, notwithstanding, 
by virtue of that providential power which, amid 
a host of obstacles and diversions, finally achieves 
progress. 



VI 



Many chemists, even the most illustrious, had 
devoted themselves to the study of the natural 
agents of fertility, previously to M. Ville. Their 
investigations led to most important results ; but 
in spite of the advantages they offered, they left a 
general impression of insufficiency, and discour- 
agement soon succeeded enthusiasm. Anim-il 
charcoal and guano, for example, gave rich har- 
vests, but it was soon found that they were expe- 
dients, and not specifics. Even farm-yard manure 
justified the title of perfect manure but very 
incompletely. It did not always respond to 
what was required of it, and moreover is not 
sufficiently abundant to restore to the soil all that 
is taken from it, as the residues of a harvest con- 
sumed at a distance cannot all be returned to 
the field, which, it may be said, leaves us with 
exhaustion in prospective. 

So true is this that, even where manure is col- 
lected with the greatest care, the necessity for 
supplying the evil with stimulants is still felt. 
Fossil manures present themselves to supply this 
deficiency, and they certainly possess great 
value, but do they unite every quality necessarv 
to secure us against fresh disappointment? There 
lies the pith of the question. 

When agriculturists demand an analysis to test 



Yll 



the richness of a field and repair its losses after 
each harvest, they lose sight of the fact, that each 
field has its own peculiar wants, and what will 
suit one may not suit another. 

It is by stating the problem in these terms that 
M. Ville has arrived at its solution. He has 
studied the appetites of each plant, or at least, 
of those three great families of plants upon which 
agricultural industry is mostly exercised, viz : — 
the cereals, leguminous plants, and roots : and 
he has deduced from this study the formula of a 
normal manure. 

There is nothing extravagant in stating that 
light has thus replaced darkness, that order has 
succeeded to chaos, and that the phantom of 
sterility is laid. If, like all mundane things, the 
system is perfectible, the specialization of ma- 
nures — or, to speak more correctly, the nutri- 
tion of plants — is the law which will make agri- 
culture pass from the condition of a conjectural 
to that of a positive science. 

To operate with greater certainty, M. Ville 
removed every element of error or doubt from his 
experiments, and proceeded by the synthetic 
method. He took calcined sand for his soil, and 
common flower-pots for his field. Ten years of 
assiduous observation and experiment led him to 



recognize that the aliment preferred by cereals 
is — nitrogen ; by liguminous plants — potassa ; 
by roots — the phosphates: we say the pre- 
ferred element, but not the exclusive : for these 
three substances, in various proportions, are 
necessary to each and all, and even lime, which 
humus renders assimilable, must be added. 

These facts, proved in pure sand by means of 
fertilizers chemically prepared, were next re- 
peated in the soil of a field on the Imperial farm 
at Yincennes, at the expense of the Emperor, 
who, with that sagacity and tact which marks 
his every public act, recognized in M. Ville, even 
at the time he was violently opposed and unpop- 
ular, the man most capable of turning the con- 
quests of science to the advantage of agriculture : 
he extended a generous and powerful hand to 
the professor, and the most complete success has 
crowned his glorious initiative. 

During the past four years curious visitors, 
drawn to the farm by the report of M. Ville's 
experiments, have been shown a series of square 
plots, manured and sown in conformity with rules 
laid down to test their efficacy. Upon some of 
these plots the seed has never been varied ; the 
same soil has been planted four times in suc- 
cession with wheat, colza, peas, and beetroot : 



giving them, at the commencement, a supply of 
the normal manure, and adding annually what M. 
Ville terms the dominant ingredient, that is to 
say, the special manure of the series. Upon the 
other plots, the seed alternated during the qua- 
ternary period at the expense of the normal ma- 
nure, by changing the dominant according to the 
nature of each plant introduced into the rota- 
tion : and under these conditions, the crops have 
reached to results of irrefutable eloquence. 

But as a proof necessary to satisfy prejudiced 
minds, side by side with the plots which had re- 
ceived the complete manure, others were placed 
in which one or more of the elements were 
omitted. In the latter, vegetation was languid, 
and almost nil, proportionally to the quantity and 
quality of the absent ingredients, to such a de- 
gree, that what was wanting could be ascertained 
by the decrease of vigor in the plant. A little 
practice thus leads to an appreciation of the 
qualitative richness of a soil. For the suppression 
of one of the principles of fertilization produces 
in each vegetable family differences, which indi- 
cate to the observer the part which each principle 
performs, and the proportion in which it is ab- 
sorbed. These experiments, the fundamental 
bases of theory, have not, however, the reguiat- 



iiig of agricultural practice for their object. M. 
Ville assigns four years to the action of the nor- 
mal manure, replenished after each harvest by 
the dominant element; renewing this normal 
manure, however, upon the first signs of a fall- 
ing off in the crops. 

By adding, according to M. Ville's system, ni- 
trogenous matter, phosphate of lime, and po- 
tassa, — that is to say, a normal or complete ma- 
nure to calcined sand, the seed-wheat being- 
equal to 1, — the crop is represented by 23. 

Upon withdrawing the nitrogenous matter 
from this mixture of the four elements, the crop 
fell to 8.83. 

Upon withdrawing the potassa, and retaining 
all the others, the crop only attained to the figure 
6.57. 

When the phosphate of lime was omitted, the 
crop was reduced to 0.77 : vegetation ceased, 
and the plant died. 

Lastly, upon abstracting the lime, then the 
crop, the maximum of which was represented by 
23, was only 21.62. 

From the above facts we draw these conclu- 
sions : — that if the four elements of a perfect 
manure, above named, act only in the capacity 
of regulators of cultivation, the maximum effect 



XI 

they can produce implies the presence of all four. 
In other words, the function of each element de- 
pends upon the presence of the other three. 
When a single one is suppressed, the mixture at 
once loses three-fourths of its value. 

It is to be remarked, that the suppression of 
the nitrogenous matter, which causes the yield 
of wheat to fall from 23 to 8.33, exercises ouly a 
very moderate influence upon the crop, when the 
plant under cultivation is leguminous. But it 
will be quite otherwise if, in such case, we remove 
the potassa. 

W we extend the experiment to other crops, 
and successively suppress from the mixture one 
of the four agents of production, we arrive at 
the knowledge of the element which is most es- 
sential to each particular crop, and also which is 
most active in comparison with the other two. 
For wheat, and the cereals generally, the element 
of fertility, par excellence, — that which exercises 
most influence in the mixture, — is the nitroge- 
nous matter. For leguminous plants, the agent 
whose suppression causes most damage is po- 
tassa, which plays the principal part in the mix- 
ture. For turnips and other roots, the dominant 
element is phosphate of lime. 

By employing these four well-known agents, 



M. Ville's system may well replace the old sys- 
tem of cultivation. With him, the rule that ma- 
nure must be produced upon its own domain is 
not absolute. During four succeeding years, M. 
Ville has cultivated, at the Vincennes farm, wheat 
upon wheat, peas upon peas, and beetroot upon 
beetroot: and he entertains no doubt that he 
could continue to do so for an indefinite period, 
the only condition necessary to be fulfilled being 
— to return to the soil, in sufficient proportion, 
the four fundamental elements above named. 

Suppose we wished to cultivate wheat indefi- 
nitely. We should at first have recourse to the 
complete manure, and afterwards administer only 
the dominant element, or nitrogenous matter, 
until a decrease in the successive crops showed 
that this culture had absorbed all the phosphate 
of lime and potassa. As soon as a diminution in 
the crops manifests itself, we must return to the 
complete manure, and proceed as before. 

Suppose that, instead of an exclusive culture, 
it be desired to introduce an alternate culture in 
a given field. We commence with the agent 
that has most influence on the plant with which 
we start. If that be a leguminous plant, we 
at first administer only potassa. For wheat, 
we should add nitrogenous matters. If we con- 



Xlll 



elude with turnips, we have recourse to phos- 
phate of lime ; but when we return to the point 
from which we started, all four elements must be 
employed. 

As may be seen, this system differs radically 
from that hitherto adopted. It has not for its 
basis a complex manure administered to the soil 
by wholesale, in which we endeavor to turn all 
its constituents to account by a succession of 
different crops. In M. Ville's system, he sup- 
plies to the soil only the four governing agents 
of production, which are added gradually, one 
after another, and in such manner as to supply 
each kind of crop with the agent that assures the 
maximum yield. 

The experiments at Vincennes were quite con- 
clusive, but M. Ville wished to verify them on a 
larger scale. For this purpose, land on the estate 
of Belle Eau, near Donzere, in Dauphiny, was 
placed at his disposal wherein to open a new field 
of experiments. The results were just the same. 
On the 4th of July last, an audience of two hund- 
red farmers, and others interested in the progress 
of agriculture, assembled under the lofty trees at 
Belle Eau, to listen to the professor's explana- 
tions and witness the proofs of the soundness of 
his new system. 



XIV 

He stated that the experimental field, divided 
into seven equal portions, was sown in November 
last with " Hallett Wheat." One portion received 
no manure at all ; consequently the product, both 
ears and straw, was weak and frail. Each of the 
other portions was fertilized with one of the sub- 
stances which constitute wheat (phosphate of 
lime, potassa, lime, and nitrogen). They pre- 
sented a series of interesting products, the last of 
which — that is to say, the most advantageous as 
to yield — was reaped from that portion of the 
soil fertilized with an artificial mixture of all the 
constituent substances united. 

Devoid of all scientific nomenclature, which 
frequently embarrasses most agriculturists, M. 
Ville's lucid and brilliant expose convinced the 
most incredulous. Almost every auditor retired 
with the firm resolution of repeating the pro- 
fessor's experiments for himself. 

All manure must contain principles, mixed in 
certain proportions, the combination of which is 
indispensable. In this particular, M. Ville has 
invented nothing, but limited himself to the spe- 
cializing and better defining their effects, with- 
out, however, forgetting those which are purely 
mechanical. It remains now for practical men to 
combine and prepare fertilizers of each kind, and 



to apportion their application according to the 
rules here laid down. This is a simple detail of 
execution, and if we are compelled to have re- 
course to chemical products to complete the ele- 
ments of fertilization, they will not replace the 
residues of animal consumption, nor render them 
useless ; but will allow M. Moll's beautiful for- 
mula to subsist in ail its truth. — " The purifica- 
tion of cities by the fertilization of the country." 
We believe we do not deceive ourselves in 
affirming that the difficulties of the sewerage 
question will be removed from the minds of all, 
as they now are from those who have given 'due 
attention to the subject. 

CHARLES MARTEL. 

Ashford Cottage, Fortess Terrace, 
Kentish Town. 



ANALYSIS. 



AGRICULTURE A SCIENTIFIC PROBLEM. — ALL KNOWN PLANTS ARK 
COMPOSED OF FIFTEEN ELEMENTS ONLY, WHICH ARE SUBDIVIDED 
INTO TWO GROUPS, THE ORGANIC AND THE INORGANIC — PARALLEL 
BETWEEN VEGETABLES AND MINERALS. — THE FORMATION OF THE 
VEGETABLE DUE TO ORGANIC POWER, WHICH MODIFIES THE ORDI- 
NARY PLAY OF AFFINITES. — NATURE, UNIFORM IN HER GENERAL 
LAWS, DOES NOT PASS ABRUPTLY FROM THE MINERAL TO THE 
VEGETABLE, BUT THROUGH A SERIES OF COMPOUNDS NAMED 
TRANSITORY PRODUCTS OF ORGANIC ACTIVITY, WHICH ARE EITHER 
HYDRATES OF CARBON OR ALBUMENOIDS. — THESE PRODUCTS PASS 
INSENSIBLY FROM ONE STATE TO ANOTHER BY CHEMICAL RE- 
ACTIONS.— THE ALBUMENOIDS CONTAIN NITROGEN, AND PRESENT 
THEMSELVES UNDER THREE ESSENTIAL FORMS: INSOLUBLE, SEMI- 
SOLUBLE, AND SOLUBLE, TO WHICH THE THREE TYPES, FIBRINE, 
CASEINE, AND ALBUMEN CORRESPOND. — CHANGES THAT OCCUR 
DURING GERMINATION, AND DURING THE FORMATION OF THE SEED. 
— THE GREATER PART OF THE WORK OF VEGETATION MAY BE RE- 
FERRED TO THE RECIPROCAL ACTION OF THE HYDRATES OF CARBON, 
ALBUMENOIDS, AND MINERALS, THROUGHOUT WHICH THE GENERAL 
LAWS OF CHEMISTRY PREVAIL. — THE QUANTITY OF MINERAL 
MATTER CONTAINED IN VEGETABLES IS IN PROPORTION TO THE 
ACTIVITY OF EVAPORATION. — THE DISTRIBUTION OF THE MINERAL 
MATTER IN VEGETABLES OBEYS FIXED LAWS. — DEFINITION. — 
VEGETABLES ARE COMBINATIONS OF A SUPERIOR ORDER TO MIN- 
ERAL COMBINATIONS, BUT, LIKE THEM, DEPENDENT UPON THE AS- 
SOCIATION OF THE FIRST ELEMENTS UNDER THE INFLUENCE OF THE 
GENERAL LAWS OF CHEMISTRY. 

1 



LECTURE FIRST. 



In consequence of the persevering efforts given to 
the study of plants of late years, agricultural produc- 
tion has been raided to the rank of a scientific problem. 
It is in this spirit that I have for many years studied it 
at the Museum of Natural History. Here, my lan- 
guage will be more simple, familiar, and practical ; it 
will, nevertheless, retain its scientific character, science 
being the essential basis of every thing I have to tell 
you. 

If we seek to define the conditions which determine 
vegetable production, the influences which modify its 
growth, and the forces which govern its manifestations, 
we must commence by going back to the elements of 
vegetables themselves. We must separate from the 
vegetable its organic individuality, and consider only 
the chemical combinations of which it is the seat and 
the result. 

The analysis of all known vegetables or the products 
extracted from them, leads to this very unexpected 
fact, — that fifteen elements only concur in these innu- 
merable formations. These fifteen elements, which, 
2 



alone, serve to constitute all vegetable matter, are sub- 
divided into two groups : — 

First — The organic elements, which are encountered 
only in the productions of organized beings, and the 
source of which is found in the air, and in water. 

They are Carbon. Oxygen. 

Hydrogen. Nitrogen. 

Second — The mineral elements, which resist com- 
bustion, and which are derived from the solid crust of 
the globe. 

They are Potassium. Phosphorus. 

Sodium. Chlorine. 

Calcium. Iron. 

Magnesium Manganese. 

Silicium. Aluminium. 
Sulphur. 

Vegetables are, in fact, and from the special point 
of view where we place them, only the varied combi- 
nations of which these fifteen elements are susceptible. 
In the same way that a language expresses our most 
delicate and profound thoughts, as well as the meanest, 
by means of the small number of letters which compose 
its alphabet — so do vegetable productions assume the 
most varied forms and dissimilar properties by means 
of these fifteen elements only, which compose the true 
alphabet of the language of nature. 

Now, if it be so, we are justified in likening the 



4 



vegetable to a mineral combination, a more complicated 
one, doubtless, but which we may hope to reproduce in 
every part, by means of its elements, as we do with 
the mineral species. This proposition, how astonishing 
soever it may appear to you, is nevertheless the exact 
truth. To prove it to you, permit me to establish a 
parallel between vegetables and minerals, from the dif- 
ferent points of view which more especially character- 
ize the latter. We will commence with their mode of 
formation and growth. 

First, we perceive only differences. A crystal sus- 
pended in a saline solution, grows by the deposit of 
molecules on its surface, similar in composition and 
form to those which constitute its nucleus. These 
molecules, diffused through the solution, obey the laws 
of molecular attraction, and thus increase the mass of 
the primitive crystal. The vegetable, on the contrary, 
does not find diffused vegetable matter in the atmosphere, 
nor in the soil with which it is in contact. Through 
its roots and leaves it derives its first elements from 
without, causing them to penetrate into its interior, and 
there mysteriously elaborates them to make them ulti- 
mately assume the form under which they present 
themselves to our eyes. 

We can, nevertheless, say that the process of vegeta- 
ble production has something in common with the for- 
mation of a mineral. For in both cases we see a cen- 
tre of attraction, which gathers up the molecules, &c, 
received from without. In the more simple case of the 



mineral, the combination of the elements is previously 
accomplished; only a mechanical grouping takes place. 
In the more complex case of the vegetable, the combi- 
nation and mechanical grouping are effected at the same 
time, and in the very substance of the plant. In both 
cases a formation is engendered by the union of definite 
or definable material elements. 

From the point of view of composition, vegetables 
appear at first more simple, since they are derived from 
fifteen elements only, while at least sixty concur in the 
production of minerals ; but in reality they are more 
complex, since each plant always contains the fifteen 
elements at once, while minerals, taken individually, 
never contain but a very small number, five or six at 
most. Among vegetables, the combination is also more 
intimate. In minerals, each of the constituents pre- 
serves up to a certain point, its individual properties. 
In the sulphates, for example, it is easy to prove the 
presence of sulphuric acid by adding baryta to it, which 
gives the insoluble precipitate of sulphate of baryta in 
these salts as well as in sulphuric acid itself. Besides, 
in thus withdrawing the sulphuric acid from a sulphate, 
we have not destroyed the sulphuric acid, we have only 
displaced it. But with the group of elements which 
form a vegetable, it is not so ; in them, all individual 
character disappears. Who can perceive the carbon, the 
nitrogen, the potassa, &c, which constitute the plant? 
Only the whole manifests its properties, and we cannot 
separate an element from it, except by destroying it 



6 



past recovery. Notwithstanding these essential differ- 
ences, we have, nevertheless, in both cases, to do with 
material combinations, that is to say, with phenomena 
of the same nature, one of which is more complicated 
than the other ; they are two distant terms of the same 
series. 

Let us conclude this parallel by comparing the forces 
which, in both cases, determine the grouping of the 
elements. When attraction is exercised at great dis- 
tances, in the planetary spaces, for example, it depends 
only on the reacting masses, and not upon their nature ; 
when, on the contrary, attraction is exercised in contact, 
as in chemical combinations, it depends at the same 
time upon the mass and the nature of its elements. 
This new and more complex form of general attraction 
is called affinity. Gravitation, the first term of the 
series, which we call universal attraction, governs and 
harmonizes the movements of the stars ; affinity, the 
second term of this same series, regulates the play of 
mineral combinations. 

If we examine the formation of vegetables from this 
point of view, we shall see that it represents a still 
more complicated case of universal attraction, a third 
term of the series, if I may be allowed the expression. 
Here, in fact, the result depends at the same time on 
the re-acting masses, on the nature of the elements 
present, and on the action of a new force, situated in 
the embryo, which diffuses itself from thence through- 
out the vegetable, and impresses its special stamp upon 



the combination produced. Take two seeds of the 
same sort, having the same weight, remove from each 
of these seeds a morsel also of the same weight, only 
let one include the embryo in the amputation, and in 
the other let the embryo be left out, and take instead a 
fragment of the perisperm, then put both upon a wetted 
sponge. The seed without embryo will soon enter into 
a state of putrefaction, the other, on the contrary, 
will give birth to a vegetable capable of absorbing and 
organizing all the products resulting from the disor- 
ganization of the first. There is then in this embryo 
a new power, of organic essence, which modifies the 
ordinary course of affinities, and impresses upon the 
combinations present a special form, of which it is itself 
the prototype. 

The formation of the vegetable is not the only case 
where foreign forces come thus to modify the ordinary 
play of affinities. Mix hydrogen and nitrogen together 
in the dark, there will be no combustion. Submit the 
mixture to the action of the solar rays, an explosion 
immediately takes place, and the gaseous mixture is 
replaced by a new product — hydrochloric acid. Here 
then are two elements incapable of entering into com- 
bination by themselves, but which acquire this faculty 
by the intervention of a foreign force — light. Min- 
eral chemistry abounds in examples of this kind. 

In the greater complication of vegetables under these 
different relations, I consider it then to be correct not 
to see a sufficient reason for believing that nature has 



8 



traced a line of absolute demarcation between minerals 
and vegetables, nor to admit that the laws of their for- 
mation have nothing in common with those better known 
laws which regulate the productions of the inorganic 
kingdom. I think, on the contrary, that nature is 
uniform in her general laws, and that by attentive ob- 
servation aided by experiment, we may arrive at know- 
ing them in all their effects. I perceive then nothing 
irrational in the attempt to arrive at the artificial reali- 
zation of the conditions in which they are exercised to 
produce vegetables, as science has already succeeded 
in doing with minerals. This conclusion will acquire, 
I hope, a stronger and stronger evidence as we pene- 
trate deeper in our researches, and I shall at once give 
a very striking confirmation of it, in showing you that 
nature does not pass suddenly from the mineral to the 
vegetable, from crude matter to organized matter, but 
that there exists, on the contrary, a class of compounds 
which lead us insensibly from the one to the other, and 
form the bridge which unites these two series of pro- 
ductions. These compounds which, for this reason, we 
name transitory products of organic activity, range 
themselves in two different groups — hydrates of car- 
bon and albumenoids. The following is an enumera- 
tion of them. 



9 



TRANSITORY PRODUCTS OF ORGANIC ACTIVITY. 
Hydrates of Carbon. Albumenoids. 

ta«b-...{jj5*"> }Kbn„e. 

( Gum Tragacanth, "> 
Semi-Soluble 1 Mucilages, >• Caseine. 

( Pectine, ) 

( Gum Arabic, } 
Soluble. . . . < Dextrine, . >- Albumen. 

( Sugars, ) 

Let us first examine the hydrates of carbon. 

Considered separately, these bodies appear very un- 
like each other. 

Cellulose, which is the prime material of all vegeta- 
ble tissues, is hard, insoluble in water, and resists the 
action of most re-agents. 

Starch presents itself in globules formed of concen- 
tric layers. It swells and forms a jelly with boiling 
water, or with a weak solution of potassa. Tincture of 
iodine turns it blue. 

Pectine also forms a jelly with water, but it exhibits 
no trace of organization, and iodine does not turn it 
blue. 

Mucilages swell in cold water, but do not dissolve. 

Gum Arabic dissolves in cold water. 

Lastly, Sugars dissolve and crystallize, thus present- 
ing one of the essential characteristics of mineral mat- 
ters. 

Thus all these bodies form a regular series, of which 
the types I have characterized arc only distant terms. 



10 



But in nature we find all the intermediates by which 
we can pass insensibly from each one to that which fol- 
lows it. It is thus that cellulose presents itself to us 
under very different states of cohesion, from the wood 
and perisperm of the date, where it is extremely hard, 
unto the young shoots of all kinds of vegetables, and 
the skins of fruits, where it is not more solid than 
starch paste. The latter which in the apple, potato, and 
wheat, is in solid globules, and isolated like grains of 
sand, is found in a viscid state in other plants, and thus 
passes gradually to the form of gums and mucilages. 
Butween the latter and the sugars that crystallize, we 
find the uncrystallizable sugars, &c. 

But the analogies which these bodies present with 
each other do not stop here. It is, in fact, possible to 
convert them artificially from one into another by the 
very simple re-actions of the laboratory. Under the 
influence of dilute acids and prolonged boiling, all are 
resolved into grape sugar, which seems to be the least 
organized form, the nearest to mineral nature that the 
type can assume. As if to give a superior reason to 
all these approximations, elementary analysis assigns 
one and the same formula to all the compounds. Each 
contains twelve equivalents of carbon united to the ele- 
ments of water, and may be thus represented — 

C 12 (HO) n 

(Carbon.) (Water.) 

which entitles them to the denomination of hydrates of 



11 

Beside this series of ternary compounds, we also 
find in all vegetables, the albumenoids which, to the 
three elements above indicated, join a fourth, nitrogen, 
in an important quantity, and two others, sulphur and 
phosphorus, in very small proportions. 

These compounds, much more complex than the first, 
present themselves under three essential forms : insolu- 
ble, semi-soluble, and soluble, to which the three types, 
fibrine, caseine, and albumen respond. Like the pre- 
ceding, they are met with in nature under very varied 
conditions, and may be converted, one into another, by 
the reactions of the laboratory. 

The hydrates of carbon and the albumenoids form 
then two parallel series, which exist side by side in the 
substance of all vegetables, and which are constantly 
undergoing the various transformations of which they 
are susceptible. 

Let us show what takes place during the germination 
of a grain of wheat. The hydrate of carbon exists in 
the dried grain under the form of starch, and the albu- 
menoid under the form of fibrine or gluten. In pro- 
portion as the water penetrates the perisperm, it swells, 
becomes milky, and then it contains albumen, and dex- 
trine, and true gum. Subsequently, when the blade is 
elongated, when the leaf begins to respire, you will find 
sugar and cellulose, which are produced at the expense 
of the original starch. By the side of these bodies you 
will find albumen derived from the gluten. 

Let us examine on the other hand what takes place 



12 



during the formation of the seed. In beet-root, for ex- 
ample, sugar exists. In proportion as the seed is formed 
the sugar disappears, but on the other hand, the seed 
is full of starch. During the foliaceous life of the plant, 
its juice contains albumen ; when the seed is formed, 
the greater portion of the albumenized principle is found 
concentrated in an insoluble form. 

We are then fully justified in believing that these 
bodies are being constantly transformed into each other 
in the very substance of the vegetable, and that they 
are like the several steps of a ladder, by which crude 
matter gradually ascends to the rank of completely 
organized matter. 

But we have - seen that in the laboratory these trans- 
formations are effected by energetic chemical agents. 
What can be the cause which determines these same 
effects in the substance of the plant ? 

When sulphuric acid converts baryta into the sulphate 
of that base, it combines with it, and there no longer 
exists either baryta or sulphuric acid. The two con- 
stituents are confounded in the product of the combi- 
nation, which is sulphate of baryta. 

When the same acid converts starch or cellulose into 
sugar, things do not proceed exactly in the same man- 
ner. After the transformation, we find the acid wholly 
free. By its presence alone it acts like the solar ray 
upon the mixture of chlorine and hydrogen : and sul- 
phuric acid is not the only body which possesses this 
property. The albumenoids, of which we have just 



13 



spoken, possess it in a higher degree, especially when 
they have begun to undergo a change by contact with 
the oxygen of the atmosphere. 

Putrid gluten rapidly converts considerable quanti- 
ties of starch into dextrine and sugar, and that without 
being itself disturbed by the exercise of its own modi- 
fications. The cause of the changes which the hydrates 
of carbon undergo in the substance of vegetables resides 
therefore in their encounter with the albumenoids, which 
are themselves modified under the influence of water, 
the oxygen of the atmosphere, and the mineral agents 
derived from the soil. 

We may then, finally, refer the greater part of the 
work of vegetation to the reciprocal action of the 
hydrates of carbon, albumenoids and minerals. 

You perceive that all through this extremely com- 
plicated chemical operation, we always encounter the 
application of the general laws of chemistry, for the 
actions of contact are not peculiar to vegetables. They 
are also frequently encountered in the reactions which 
are effected without organic agency, only they predom- 
inate in the phenomena of vegetable life. 

The study to which we devote ourselves therefore 
warrants the parallel we have drawn between minerals 
and plants, from the point of view of the superior laws 
of their production. I shall conclude by confirming 
this resemblance, and showing you that the separation 
in the substance of the vegetable of the various elements 
composing it, is submitted to a law as well determined, 



14 



I may say, almost as geometrical, as the arrangement of 
the molecules in a crystallization. 

Let ns begin with the minerals. Considered as a 
whole, they are more abundant in grasses than in trees. 
The latter contains only 1 per 100 upon an average, 
while grasses contain from 7 to 8 per 100. 

The reason of this is very simple. In a salt marsh, 
the quantity of salt deposited in summer is more con- 
siderable than that produced in winter, because during 
summer the temperature being higher, the evaporation 
is more active. So also in vegetables, the quantity of 
mineral matter they contain is great in proportion to 
their evaporation. Now herbage being in contact with 
the atmosphere in every part, it is the seat of an evapo- 
ration much more active than that in trees, which con- 
tain completely sheltered organs. We find a rigorous 
application of this law in the tree. The sapwood con- 
tains less mineral matter than the heart, the heart less 
than the bark, the bark less than the leaves. In the 
green leaves of trees there is less than in the leaves 
that fall in autumn. 

In leguminous plants, the pod is richer than the seed, 
and in the seed there is more in the skin than in the 
bean. The distribution of mineral matter in the sub- 
stance of a vegetable obeys therefore an invariable law, 
it is in direct relation with the activity of evaporation. 
If we examine what takes place with regard to the 
nature of the elements, we see that here also fixed lavvs 
prevail. Phosphoric acid, potassa, and magnesia pre- 



15 



vail in the seeds, the alkaline earths and iron on the 
contrary prevail in the stalks. 

The alkalies increase in proportion as we approach the 
fruit and young shoots. They are much less abundant 
in those organs which are old and have less vital activity. 

Phosphoric acid is disseminated in a nearly uniform 
manner throughout the vegetable, and suddenly increases 
when it arrives at seeding. 

As to the organic elements, the laws are no less pre- 
cise. Carbon, oxygen, and hydrogen, which, in the 
state of hydrates of carbon, form the general framework, 
are found diffused nearly uniformly throughout all the 
organs. Nitrogen, which forms an essential portion of 
the albumenoids, of which the most important part con- 
sists in the active task of the formation of the tissues, 
is found in the greatest quantity in all the recent shoots, 
and especially in the seed, the last product of annual 
vegetable activity. 

We have arrived in this lecture at denning vegeta- 
bles as material combinations of an order superior to 
mineral combinations, but like them, dependent upon 
the association of the first elements under the influence 
of the general laws of chemistry. This definition leads 
us invincibly to the hope of producing them artificially, 
and in every part, by means of their elements placed 
at our disposal, under conditions where they are suscep- 
tible of assuming this kind of combination. It remains 
for us to examine the means we can employ to attain 
this aim. 



ANALYSIS. 



THE ORGANIC ELEMENTS OF VEGETABLES ARE OXYGEN, HYDRO- 
GEN, CARBON, AND NITROGEN. — UNDER WHAT INFLUENCES AND 
CONDITIONS THESE ELEMENTS ENTER THE VEGETABLE FROM WITH- 
OUT. — CARBON ENTERS THE PLANT UNDER THE FORM OF CARBONIC 
ACID, WHICH IS ABSORBED BY THE ROOTS, AND BY GREEN LEAVES 
UNDER THE INFLUENCE OF SOLAR LIGHT, AND EMITTED FROM THE 
LEAVES DURING DARKNESS. — OXYGEN IS DISENGAGED FROM THE 
LEAVES IN EXACT PROPORTION TO THE QUANTITY OF CARBONIC ACID 
ABSORBED. — WHAT BECOMES OF THE CARBONIC ACID ABSORBED? — 
IT IS DECOMPOSED, ITS CARBON FIXES ITSELF IN THE VEGETABLE 
WHILE ITS OXYGEN IS REMOVED. — UNLIMITED SUPPLY OF CARBONIC 
ACID FROM THE RESPIRATION OF ANIMALS, FROM THE FORMATION OF 
PYRITES, AND FROM VOLCANOES. — CARBON FORMS ABOUT 50 PER 
CENT. OF DRIED PLANTS — THE QUANTITY FIXED DEPENDS UPON 
THE EXTENT OF THEIR FOLIAGE. — WATER THE SOURCE OF THE 
OXYGEN AND HYDROGEN IN PLANTS; IS SOMETIMES DECOMPOSED, 
LIKE CARBONIC ACID, THAT ITS OXYGEN MAY BE ELIMINATED.— 
PLANTS CONTAIN ONLY SMALL QUANTITIES OF NITROGEN, BUT IT IS 
AN INDISPENSABLE ELEMENT. — THEY CONTAIN MUCH MORE NITRO- 
GEN THAN IS SUPPLIED BY MANURE — WHICH EXCESS IS OBTAINED 
FROM THE ATMOSPHERE. — THE NITRATES OCCUPY THE FIRST RANK 
AMONG THE NITROGENOUS MATTERS USEFUL TO VEGETATION.— 
NEXT COME AMMONIAC A L SALTS. — SOME CROPS DO NOT REQUIRE 
THE ADDITION OF NITROGEN TO THE SOIL. — THE CEREALS REQUIRE 
THIS ADDITION IN LARGE QUANTITIES. 
17 



LECTURE SECOND. 



In our first discourse we arrived at the consideration 
of the vegetable as a material aggregate, having the 
closest analogy with chemical combinations. We have 
seen that the laws which preside at its formation differ 
in no respect, in a philosophical point of view, from 
those which regulate the production of the compounds 
of mineral chemistry. 

If it be so, in order to penetrate the mysteries of the 
production of vegetables, the first thing we have to do 
is to ascend to the origin of their elements, and after- 
wards inquire in what conditions, and under what 
influences, these elements enter from without, and com- 
bine together in a special manner to produce the vege- 
table. 

Let us commence this study with the organic ele- 
ments, which are : 

Carbon. Oxygen. 

Hydrogen. Nitrogen. 

The carbon cannot penetrate vegetables, except under 



19 



the form of carbonic acid. This gas arrives by two 
different ways. 

1st. By the roots, which draw it from the soil, where 
it is produced by the spontaneous decomposition of 
organic matters. 

21. By the leaves, which take it from the atmos- 
pheric air, where it exists permanently. 

In order for the carbonic acid to be absorbed, it is 
necessary that four essential conditions be realized. 

The first is of organic nature, and resides in the 
green color of the organs of vegetables. The petals 
of flowers which are variously colored do not absorb 
carbonic acid : the leaves, the bark, and the pericarp 
of green fruits, on the contrary, absorb it in abun- 
dance. In the generalization of this fact it may be 
objected that purple leaves, and leaves that are almost 
white, exist, which also absorb carbonic acid from the 
air. I find the reply in a recent work by M. Cloez. 
This chemist has shown that the leaves referred to, not- 
withstanding their different aspect, contain large quan- 
tities of green matter. It is, then, safe to say that the 
function under consideration depends upon this green 
matter. 

Whatever the color of the organs, carbonic acid is 
never absorbed in the absence of solar light. This 
second external condition of the vegetable is also as 
indispensable as the first. Would you wish to prove 
it ? Pass a current of air into a large receiver contain- 
ing a young vine with its leaves, and connected with an 



20 



apparatus capable of measuring carbonic acid. You 
will perceive, as M. Boussingault has done, that in the 
sun, the atmospheric air, in passing over the green 
leaves, loses nearly one-half its carbonic acid, while in 
the dark, on the contrary, it gains a very considerable 
quantity. Not only, then, the leaves absorb no car- 
bonic acid in the dark, but they also constantly emit it, 
to the destruction of a portion of their substance. 
"When the leaves are attached to the plant, they disen- 
gage more carbonic acid than when they are removed, 
because that which the roots derive from the soil, not 
being decomposed in the vegetable, comes then to be 
exhaled from the surface of the leaves. 

A third indispensable condition, also, is the interven- 
tion of a certain temperature. MM. Grratiolet and 
Cloez have shown that the leaves of the potamogeton, 
which, in water at 54° F., disengages abundance of 
oxygen, ceases to do so when the temperature is low- 
ered to 37° F. Now, as we shall soon see, this disen- 
gagement of oxygen is precisely the certain index of 
the absorption of carbonic acid. 

Finally, the fourth and last condition of the pheno- 
menon is the presence of oxygen in the atmosphere in 
which the leaves are placed. Theodore de Saussure 
has proved that in an atmosphere of hydrogen or nitro- 
gen, containing carbonic acid, this gas is not absorbed 
by plants. On the contrary, the phenomenon manifests 
itself whenever oxygen forms a portion of the surround- 



21 



What becomes of the carbonic acid thus absorbed 
by plants ? While this substance resists the highest 
temperatures and the most powerful chemical reducing 
agents, in the substance of plants this acid is decom- 
posed, its carbon fixes itself in the vegetable, and its 
oxygen is removed. Hence the disengagement of 
oxygen which takes place on the surface of leaves 
immersed in water. This fact, one of the most impor- 
tant which science has discovered in this century, has 
been brought to light by the labors of a whole gener- 
ation of savants, but it was principally by Theodore de 
Saussure that the conditions were defined. He saw 
that the quantity of oxygen emitted was equal in vol- 
ume to the carbonic acid absorbed, and that minute 
quantities of nitrogen were disengaged. This disen- 
gagement of nitrogen, since proved by MM. Gratiolet 
and Cloez, has recently been denied by M. Boussin- 
gault. 

Not wishing to insist upon this point, which has no 
interest in agriculture, I shall merely remark that, in 
all the experiments made, one condition, which could 
alone give value to their results, has been wanting. 
For it to be legitimate, in fact, to extend to vegetation 
the facts observed in these experiments, they must be 
performed upon vegetables in progress of development, 
constantly increasing in weight, and not upon detached 
portions, which may, it is true, still give vital manifes- 
tations, but the ephemeral existence of which is neces- 
sarily accompanied by special phenomena of destruc- 
tion. 



22 



The assimilation of the carbon, so interesting in a 
physiological point of view, presents only an insignifi- 
cant interest for agriculture : there need be no fear of 
its ever failing, for the atmosphere contains an unlimited 
supply of it. In proportion as vegetation appropriates 
it, animal respiration, by an inverse effect, restores it 
in equivalent quantities. This harmony between the 
two organic kingdoms, first observed by Priestley, and 
so brilliantly explained by Dumas in his Statistics of 
Organized Beings, is nevertheless only an infinitely 
small one among the causes of the permanence of the 
atmospheric carbonic acid. 

Among geological phenomena, causes of loss exist 
which are much more powerful than vegetable absorp- 
tion. The disintegration of felspars removes colossal 
quantities of this acid from the air, but volcanoes and 
the formation of pyrites constantly restore it in quan- 
tities no less important, so that its composition presents, 
under this relation, quite a satisfactory stability for 
agriculture. 

Carbon enters into the composition of all plants in 
the proportion of about 50 per 100, when they are 
dried. It is to this element that the variation in the 
weight of crops is due. The quantity plants assimilate 
depends, in great measure, upon the surface of their 
leaves, and also a little upon their special nature. 
Experiment has proved that plants which, upon an 
equal surface of ground, fixed most carbon, were those 
that presented the greatest foliaceous surface. We 



23 



have seen, also, that with an equal surface of leaves, 
plants fix quantities of carbon differing a little accord- 
ing to the species. 

The oxygen and hydrogen found in vegetables are 
undoubtedly derived from water; this latter may be 
assimilated naturally, as is proved by the existence of 
hydrates of carbon in the substance of vegetables in 
which oxygen and hydrogen are found in the propor- 
tions necessary to form water. But the formation of 
resins, essential oils, and fat bodies, in which hydrogen 
predominates, shows that in certain cases, water may 
be reduced, like carbonic acid, and that its oxygen may 
be eliminated. Whatever it be, the origin of the oxygen 
and hydrogen once established, we have no need to dwell 
on this point, for the plants, not being deficient of water, 
are in consequence abundantly provided with these two 
elements. 

It is not the same with nitrogen. Plants contain it 
only in relatively very small quantities, but they have 
an indispensable need of it, and as in certain cases it 
may fail, it is necessary to study with the greatest care 
every thing that concerns the assimilation of this ele- 
ment. 

First let us show that all plants exhibit in the crops 
a much greater proportion of nitrogen than there was 
in the manure supplied to them. The following data 
taken from " Boussingault's Rural Economy " establish 
this fact. 



24 





Plants. 

' Potatoes 


Annual Excess of 
Nitrogen per Acre. 


Rotations of 
Five years. 


Wheat 

Clover 
Turnips 
^ Oats 

' Beach 
Oak 
Birch 


lbs. 
8-36 


Forest culture « 


29-04 




L Poplar 




Exclusive culture 


Artichokes 


37-84 


Exclusive culture 


Luzerne 


182-06 



If the crops contain such quantities of nitrogen of 
which the soil can render no account, we must look to 
the atmosphere as its origin. The air contains 79 per 
100 of elementary nitrogen : nothing appears more 
rational than to find there the origin sought. But 
chemists, accustomed to see nitrogen gas offer a great 
resistance to combination, have at first preferred to re- 
fuse to it all intervention in the phenomena of vegeta- 
tion. To restore it to the place which this preconceived 
opinion, or one founded upon incomplete experiments, 
had caused it to lose, it was necessary to have recourse 
to extremely delicate experiments, which it is impossible 
to describe in this place. 

I shall therefore content myself with refuting, by 
arguments derived from extensive cultivation, all the 
origins whfch the adversaries of the absorption of 
gaseous nitrogen are compelled to put forth, referring 



25 



to my works and to my lectures at the Museum those 
amongst you who desire to know the direct proofs of 
this absorption. 

Priestley and Ingenhouz believed in the assimilation 
of the elementary nitrogen of the atmosphere. Theo- 
dore de Saussure having proved the existence of ammo- 
nia in the air, attributed to this compound the faculty 
of supplying nitrogen to vegetables. Ammonia does 
in fact exist in the atmosphere, but the quantity is so 
small (22 grammes in 1 million kilogrammes), that it 
is evidently absurd to endeavor to make it play so im- 
portant a part. 

The objection has also taken another form. It is 
urged that the air contains ammonia Rain water dis- 
solves it, condenses it, and conveys it to the plant, 
which thus finds it in the soil. If in the place of thus 
contenting themselves with this vague assertion, they 
had thought to give it precision by measuring the am- 
monia in the rain water, and ascertaining the quantity 
of this water received per acre, they would have found 
by this way, that the soil receives, as a maximum, about 
3 pounds of nitrogen per annum. But to explain the 
vegetation of luzerne we must account for 182 pounds 
of nitrogen. The ammonia in rain water is then only 
infinitely small in relation to the phenomenon under 
consideration. 

Ammonia failing, recourse was had to nitric acid, 
which is formed in the atmosphere by the direct com- 
bination of oxygen and nitrogen under the influence of 



26 



electric discharges and during rain storms. And anal- 
ogous calculations to the preceding show that, by this 
new way also, 1 acre of land receives 3 pounds of 
nitrogen, at the most. Nitric acid therefore explains 
no better than ammonia the excess of nitrogen in the 
crops. 

But, it is urged, there may exist in the atmosphere 
some nitrogenous substance eminently assimilable, 
which is condensed by rain water, and which has hith- 
erto escaped analysis. Notwithstanding the utter 
vagueness of this objection, I have wished to reply to 
it by direct experiment. I have instituted two similar 
growths in boxes placed under shelter • one of them 
was watered with rain water collected by a pluviometer 
of equal surface to that of the box, and placed apart : 
the other received similar quantities of perfectly pure 
distilled water. The crop with distilled water was 
nearly as large as that obtained with rain water. It is 
therefore evident that rain water contained nothing 
susceptible of influencing the development of vegeta- 
bles. 

But, since it has been desired to give this importance 
to the essential products the air may yield to the soil, 
it will be permitted to me, on the other hand, to con- 
sider those which the soil yields to the atmosphere; 
and this time it is from my adversaries themselves that 
I borrow the bases of my arguments. 

M. Boussingault had the idea of collecting the snow 
from the surface of the ground and the terrace of a 



27 

garden. A litre of water from the first contained 
0*0017 gr. of nitrogen, while that from the terrace 
contained 0*0103 gr. It is certain, therefore, that cul- 
tivated soil constantly loses nitrogen. If we suppose 
that the layer of snow examined by M. Boussingault 
had a thickness of only 0*01 m. it contained in 1 acre, 
180 pounds of nitrogen lost to the soil. We sec, then, 
that the losses the soil is capable of experiencing are 
quite as important as the gains it may derive from the 
atmosphere. We must necessarily, then, have recourse 
to elementary nitrogen to explain the excess in the 
crops. 

But, here another subject of discussion presents 
itself j the nitrogen of the air — is it absorbed naturally 
by plants, as I have always maintained, or does it take 
place, as recently suggested, only by the intermedium 
of nitrification previously accomplished in the soil, 
which would thus be a real artificial nitre-bed ? Doubt- 
less, in certain cases, important quantities of nitrates 
may be produced in the soil • but I none the less per- 
sist in saying that nitrification cannot account for the 
excess of nitrogen in the crops. For the 182 pounds 
to have penetrated into the luzerne by this channel, it 
would have been necessary to engage 1756 pounds of 
nitric acid which, itself, to be saturated, must have « 
combined with 1540 pounds of bases. These 1540 
pounds of bases should be found in the crops : but, the 
latter produced upon combustion, only 1525 pounds of 
ashes, of which the bases formed 701 pounds, There 



28 

is, then, at least half the excess that the hypothesis of a 
nitrification cannot explain. 

Besides, if it were so, if the nitrogen of the crops 
came from the nitrogen formed in the soil, is it not 
evident that an artificial addition of nitrates would pro* 
duce the same effect as a natural formation ? 

Now there exists, in fact, some crops, that of wheat, 
for example, the addition of nitrates to which increases 
the yield. But there are others, as you may see for 
yourselves by inspecting the experimental field, upon 
which nitrates exercise no influence. Peas for example, 
have not assimilated more nitrogen with a strong manure 
of nitrates than without the addition of any nitroge- 
nous compound. It is then quite evident that if, in cer- 
tain cases, natural nitrification can play a definite part, 
it may, on the other hand, serve as a general explana- 
tion of the excess of nitrogen in the crops, and that the 
true and great origin of this nitrogen resides in the 
atmospheric nitrogen directly absorbed. 

And moreover, what is there, in a theoretical point 
of view, so repugnant to the admission of this absorp- 
tion ? As we speak of nitrification in the soil, who can 
deny that in the substance of leaves, where nitrogen 
undoubtedly penetrates, where it constantly meets with 
nascent oxygen, ozonised — the formation of nitric acid 
must be at least as easy as it is in the soil ? And when 
we perceive these organs endowed with a chemical power 
sufficient to reduce carbonic acid, is it then inconceiva- 
ble that they are capable of causing nitrogen to enter 



•29 

into combination more readily than it does in our labor- 
atories? No! the absorption of nitrogen, proved by 
experiment, is not irrational, and it is only habit and 
prejudices that oppose this doctrine, which, alone, is 
susceptible of giving us the clue to the phenomena of 
vegetation, and reacting usefully upon agricultural prac- 
tice. 

If the nitrogen of the air can contribute to vegeta- 
ble nutrition, is it to be said that we are not to trouble 
ourselves about supplying nitrogen to our crops, and 
that with regard to this element we find ourselves in 
the same state of security and weakness as with the 
first three that occupied our attention ? Doubtless no ! 
Practice on a large scale has proved the utility of nitro- 
genous manures, and I have myself proved that the 
yield of the cereals is considerably increased by the 
introduction of nitrogenous material into the soil. 

Of all the substances I have tried, the nitrates have 
always given me the best results, when I have operated 
on a small scale, and when the quantity of nitrogen 
supplied to the crops was inferior to that which the 
yield should have contained. On the large scale, M. 
Kuhlmann has obtained similar results. But at the 
experimental farm, at Vincennes, I have observed no 
difference between the employment of nitrates and of 
ammonial salts. This is due, doubtless, to the manures 
I had recourse to, and which I intended for several 
successive years, having been supplied in very large 



30 



quantities, and that the plants, always finding in the 
soil an excess of assimilable nitrogen, prospered as well 
in one case as in the other. 

Therefore I do not hesitate to say that I place the 
nitrates in the first rank among nitrogenous matters 
useful to vegetation. Next come ammoniacal saits, and, 
a long way after them, organic nitrogenous matters, 
which, to act usefully, must be previously converted 
into nitrates or ammoniacal salts. 

All that we have said concerning nitrogen may be 
summed up in the following conclusions, the agricul- 
tural importance of which cannot be questioned. 

1. Generally speaking, the nitrogen of the air enters 
into the nutrition of plants. 

2. In connection with certain crops, especially vege- 
tables, this intervention is sufficient, and the agricul- 
turist has no occasion to introduce nitrogen into the 
soil. 

3. With regard to the cereals, and particularly dur- 
ing their early growth, atmospheric nitrogen is insuffi- 
cient, and to obtain abundant crops it is necessary to 
add nitrogenous matters to the soil. Those which best 
fulfil this object are the nitrates and ammoniacal salts. 



ANALYSIS. 



ON THE ASSIMILATION OF MINERAL ELEMENTS WHICH PENETRATE 
THE PLANT IN AQUEOUS SOLUTION ONLY. — THE MEDIUM FROM 
WHENCE THE ROOTS OBTAIN THEM. — THE SOU- IS THE SUPPORT OF 
THE ROOTS, THE RECIPIENT OF THE SOLUTION THAT FEEDS THEM, 
AND THE LABORATORY WHERE THIS SOLUTION IS PREPARED: IT IS 
COMPOSED ESSENTIALLY OF THREE CONSTITUENTS — HUMUS, CLAY, 
AND SAND. — PROPERTIES OF HUMUS: ITS INFLUENCE IN THE SOIL, 
FIXES THE AMMONIA — IS A CONSTANT SOURCE OF CARBONIC ACID 
WHICH DISSOLVES THE MINERAL MATTERS, AND IS THE PRINCIPAL 
AGENT IN SUPPLYING PLANTS WITH THEIR MINERAL CONSTITUENTS. 
— UTILITY OF CLAY IN ARABLE LAND — IMPARTS CONSISTENCE TO 
THE SOIL, RETARDS THE PASSAGE OF WATER, FIXES AMMONIA, AND 
REMOVES A LARGE QUANTI1Y OF SALTS FROM SALINE SOLUTIONS, 
STORING THEM UP FOR FUTURE SUPPLY.— ESTABLISHES AN EQUI- 
LIBRIUM BETWEEN SEASONS OF DROUGHT AND RAINY WEATHER.— 
SAND FORMS PART OF EVERY SOIL; FORMS ITS PRINCIPAL CONSTITU- 
ENT, COMMUNICATING TO IT ITS PRINCIPAL PHYSICAL PROPERTIES, 
ESPECIALLY ITS PERMEABILITY TO AIR AND RAIN WATER — IT TEM- 
PERS THE PROPERTIES OF CLAY. — ELEMENTS OF THE SOIL, WITH- 
OUT WHICH VEGETABLE LIFE IS IMPOSSIBLE : PHOSPHATE OF LIME, 
POTASSA AND LIME, WHICH ASSOCIATED WITH A NITROGENOUS SUB- 
STANCE, AND ADDED TO ANY KIND OF SOIL, SUFFICE TO RENDER IT 
FERTILE. — CHEMICAL ANALYSIS FAILS WHEN AFPLIED TO SOILS — 
NECESSITY FOR SUBSTITUTING AN ARTIFICIAL KNOWN COMPOUND 
IN EXPERIMENT, TO REMOVE ALL SOURCE OF ERROR. — RESULTS 
OBTAINED— 1. WITH CALCINED SAND ALONE. 2. WITH CALCINED 
SAND, AND NITROGENOUS SUBSTANCES. 3. WITH CALCINED SAND AND 
MINERAL SUBSTANCES. — EACH AGENT OF VEGETABLE PRODUCTION 
EXERCISES A DOUBLE FUNCTION. 1. AN INDIVIDUAL FUNCTION 
VARIABLE ACCORDING TO ITS NATURE. 2. A FUNCTION OF UNION. — 
SPECIAL ACTION OF NITROGENOUS MATTER AND MINERAL SUB- 
STANCES. — RESULTS. —A SOIL CAPABLE OF PRODUCING PLANTS, MUST 
CONTAIN IN AN ASSIMILABLE FORM, NITROGENEOUS MATTER, PHOS- 
PHATE OF LIME, POTASSA, AND LIME. — ERRORS COMMITTED IN 
APPLYING MANURE TO SOILS THE COMPOSITION OF WHICH IS UN- 
KNOWN.— THE SOURCE OF ERROR REMOVED BY THE EXPERIMENTS 
NOW DESCRIBED. — PROSPECT OPENED BY SCIENCE TO AGRICULTURE. 
31 



LECTURE THIRD. 



The logical order of our inquiries conducts us imme- 
diately after the assimilation of the organic elements 
treated of in our last lecture, to the same question in 
respect to the mineral elements. But these bodies 
penetrate the vegetable only under the form of aqueous 
solution, and before showing you the effects they pro- 
duce, when absorbed, it is necessary that I should make 
known to you the medium from whence the roots derive 
them. 

The soil is, at the same time, the support of the roots, 
the recipient of the solution that feeds them, and the 
laboratory where this solution is prepared. It is com- 
posed essentially of three constituents, which concur, 
each in a certain proportion, to give to the whole the 
properties which I proceed to enumerate. They are 
humus, clay, and sand. 

Humus is of organic origin. It possesses a deep 
brown color, almost black. It is the cause of the dark 
color of vegetable mould. It dissolves in alkalies, with 
which it produces an almost black liquor. Acids sep- 
arate it from this solution under the form of a light, 

32 



33 



flocculent precipitate of a deep brown color. While it 
remains moist it will dissolve slightly in water, but 
when once it is dried it will no longer dissolve in it. 
It does not crystallize ; and under the action of heat 
it is decomposed, leaving a carbonaceous residue. 

Such are the properties which chemists assign to 
humus, but there is nothing very characteristic, noth- 
ing to show that humus is of a very definite chemical 
species. In fact, chemistry experiences the greatest 
difficulties whenever it attempts to specify a body which 
does not crystallize, and which is not volatile. For in 
that case we can proceed only by way of induction. 
This is what we shall attempt to do in order to arrive 
at a clear idea of the constitution of humus. 

If we submit to the controlled action of heat the 
hydrates of carbon described in our first lecture, sugar 
for example, it will not be long before we produce a 
brown body which is designated by the name of cara- 
mel. The chemical composition of this caramel is 
nearly the same as that of the sugar from whence it is 
derived, showing that the only difference existing be- 
tween them consists in the loss experienced by the 
sugar of a certain quantity of water. Sugar being 
represented by the formula C 12 H 12 O 12 or C 12 (IIO) 12 , 
caramel is expressed by C 12 (HO) 9 . When we act 
upon sugar with hot baryta water, we obtain another 
brown body, apoglucic acid or assamare, containing still 
less water than caramel. By the action of an excess 
of alkali upon sugar we descend to melassic acid, which 
•3 



34 



always contains hydrogen and oxygen in the propor- 
tions necessary to form water, bnt in still less quantity 
than the preceding bodies. 

It is then possible, by the reactions of the laboratory, 
to remove successively from the hydrates of carbon, 
and, as it were, molecule by molecule, the greater part 
of the water that enters into their composition, without 
their departing in consequence, from the original type, 
as in these various products the carbon always remains 
associated with the elements of water, and all may be 
represented by the general formula of hydrates of car- 
bon C 12 (HO) n . 

Now this gradual decomposition of the hydrates of 
carbon goes on incessantly in arable land, where vege- 
table debris of all kinds is buried. 

Humus is nothing more than the ordinary limit of 
this decomposition. Some chemists assign to it the 
formula C u H 9 O 9 ; but it is rather a collection of every 
kind through which the progressive decomposition of 
the hydrates of carbon passes, and I have no doubt 
that we can go much beyond the formula expressed by 
C 24 (HO/. Coal, studied from this point of view, fur- 
nishes us with valuable instruction. 

Death thus realizes a series of phenomena exactly 
the reverse of those produced in the substance of liv- 
ing vegetables. For while, among these latter the car- 
bon, reduced from carbonic acid, fixes upon the elements 
of water in greater or lesser proportion to produce all 
the hydrates of carbon,-— in the soil, on the contrary, 



35 



the water separates little by little from the carbon to 
arrive finally at leaving it almost in a state of liberty. 

If the chemical properties of humus are difficult to 
characterize, its presence in the soil is none the less 
useful to agriculture. It absorbs water with great 
energy, and greatly increases in volume under its influ- 
ence. By this property it contributes to maintain the 
coolness of the soil by retarding its drying. 

When humus is put in contact with an ammoniacal 
solution, it removes the ammonia from it, hue retains 
it only by a very feeble affinity, for it is only n cessary 
to introduce a large quantity of water to recover it. 
However, it does not fix combined ammonia ; that is to 
say, when it is combined in ammoniacal salts. Mixed 
with carbonate of lime or marl, does it acquire the 
faculty of fixing ammoniacal salts also ? 

By this manner of comporting itself with ammonia 
and ammoniacal salts, the utility of which are recog- 
nized in our previous lecture, humus renders important 
services to vegetation. It prevents, at least partially, 
the loss of the ammonia which results from the spon- 
taneous decomposition of nitrogenous organic matters 
buried in the soil. 

Moist humus, exposed to the air, undergoes a slow 
combustion which makes of it a constant source of 
carbonic acid. The part played by this acid in vegeta- 
ble nutrition is of the highest importance, as was 
shown in the preceding lecture : still the small quantity 
produced by the decomposition of humus can scarcely, 



86 



by its direct absorption, favor the development of plants 
which otherwise find it abundantly in the atmosphere. 
Besides, we do not attach very great importance to the 
humus under this relation. But the carbonic acid 
which it unceasingly produces in the soil fulfils another 
function, incomparably more useful. It serves to dis- 
solve the mineral matters, phosphates, alkalies, lime, 
magnesia, iron, etc. It causes the disaggregation of 
fragments of rocks containing useful matters which 
water alone cannot attack, and which, without it, would 
remain inert in the soil. Carbonic acid derived from 
humus is then, as a whole, the principal agent of solu- 
tion capable of supplying plants with their mineral ali- 
ment. 

Clay intervenes no more directly than humus in veg- 
etable nutrition. Nevertheless, its presence in arable 
land is of unquestionable utility. Clay is a hydrated 
silicate of alumina, retaining its water with great per- 
sistence, forming with it a very plastic paste, which 
serves to fabricate pottery. Its presence in the soil 
imparts consistence to it, diminishes its permeability, 
and maintains its coolness by retarding the passage of 
water. Like humus, clay fixes ammonia by a kind of 
capillary affinity, but it also possesses this property with 
regard to all saline solutions. By its agency the solu- 
ble salts resist flowing waters; still more, it removes 
from highly charged saline solutions a much larger 
quantity of salts, and yields them up again to the water 
when it arrives in sufficient quantity. In a very fertile 



37 



soil, that is to say, one much charged with soluble salts, 
when little water is present, the solution it produces 
miirht attain to such a decree of concentration as to 
oecome injurious to plants. 

In this case, the clay, by appropriating the greater 
part of the salts, sufficiently weakens the solution. If, 
on the contrary, abundant rain fails, the clay gives up 
what it had previously taken, and thus re-establishes 
the equilibrium between seasons of drought and rainy 
weather. 

In these circumstances, the clay acts as a sort of 
automatic granary, which, out of its abundance, stores 
up superfluous aliments to distribute them again when 
scarcity prevails. It regulates the strength of the ali- 
mentary solution, as the fly-wheel of a steam engine 
regulates its motion. 

As for the sand, it forms part of all soils, of which 
it is the essential constituent. It communicates to the 
soil its principal physical properties, and its permea- 
bility to air and water. It tempers the properties of 
the clay, and by its association with it, realizes the con- 
dition most favorable to the development of plants. 

We have studied the inert elements of the soil, those 
which enter into its composition to at least 99 per 100, 
but which, nevertheless, concur in vegetable production 
only by their physical properties. It now remains for 
us to examine the elements which exist in but very 
slight proportions in the soil, but of which the part 
played is capital in the life of plants, since without 
them vegetation is impossible. 



38 



Here, as with the organic elements, we commence by 
removing from the discussion the principles which are 
found in sufficient quantity in all soils, and of which, 
consequently, agriculture has no need to concern itself. 
For this reason we pass by in silence, silica, magnesia, iron, 
manganese, chlorine, and sulphuric acid. Phosphate of 
lime, potassa and lime remain. These are the essential 
minerals, such as, associated with a nitrogenous substance 
and added to any kind of soil, suffice to render it fertile. 
With them we can actually fabricate plants. 

At the commencement of my experiments, fifteen 
years ago, struck with the weakness of the old chemists 
with regard to the problems raised by vegetation, a 
weakness which I shall account for in my next lecture, 
I decided upon attempting a new method. The soil 
could not be known with accuracy, for chemical analy- 
sis had completely failed in ascertaining its composition. 
I resolved to substitute for it an artificial mixture, all 
the elements of which were clearly defined. In this way 
I arrived at producing vegetation, in pots of china bis- 
cuit, with calcined sand and perfectly pure chemical 
products. 

In these ideal conditions I instituted the four follow- 
ing experiments : — 

1. Calcined sand alone. 

2. Calcined sand with the addition of a nitrogenous 
substance. 

3. Calcined sand with minerals only (phosphate of 
lime, potassa and lime J. 



39 



4. Calcined sand with the minerals and a nitrogen- 
ous substance. 

I sowed on the same day, in each pot, 20 grains of 
the same wheat, weighing the same weight, and kept 
the soils moist with distilled water during the entire 
duration of vegetation. At the harvest I observed the 
following facts. 

In the sand alone the plant was very feeble ; the 
crop dried weighed only 93 grains. 

In the nitrogenous substance alone, the crop, still 
very poor, was however better; it rose to 140 grains. 

In the mineral alone, it was a little inferior to the 
preceding; it weighed 123 grains. 

But with the addition of the minerals and the nitro- 
genous substance, it rose to 370 grains. 

From this first series of experiments we conclude 
that each of the agents of vegetable production fulfils 
a double function : 

1. An individual function variable according to its 
nature, since the nitrogenous matter produces more 
effect than the minerals, and as either, employed separ- 
ately, raises the yield above what the seed could pro- 
duce by itself in pure sand. 

2. A function of union, since the combined effect of 
the nitrogenous substance and the minerals is very su- 
perior to what each of these two agents produces sep- 
arately. 

]>ut it is not sufficient to prove the relation of de- 
pendence which exists between the action of the nitro- 



40 



genous matter and the minerals, taken en masse ; we 
must take account of the special action of each of them. 
Let us then institute new experiments, in which we 
associate variable mineral mixtures with a nitrogenous 
substance, always the same, and employed in the name 
quantity. 

Let us commence by suppressing, among the miner- 
als first employed, the phosphate of lime, and in its 
stead associate, with the nitrogenous matter, a mixture 
composed only of lime and potassa. 

In these new conditions, vegetation is not possible. 
The seeds germinated and scarcely arrived at 4 inches 
in height; the plants withered and died. A mixture 
of potassa and lime is therefore injurious to vegetation. 
To make it useful, phosphate of lime must be added. 
Do you wish to prove it ? Make a fresh experiment 
with the same agents and a trace of phosphate of lime, 
0.01 grains in 1000 grains of soil, and you will obtain a 
plant — meagre, it is true — but which does not wither 
and die. When the phosphate of lime is in sufficient 
quantity, the crop rises to 370 grains, as before stated. 

There exists, then, between the phosphate of lime 
on the one part and the potassa and lime on the other, 
a relation of unity analogous to that which we have 
shown to exist between nitrogenous matter and miner- 
als. 

To render an account of the part played by potassa, 
let us make a fresh experiment, from which we will 
banish this alkali, and in which, consequently, the soil 



41 



will be fertilized with the nitrogenous matter and a mix- 
ture of lime, and phosphate of lime. 

Here the plant does not die, but the crop is inferior 
to that given by nitrogenous matter alone j it descends 
to 123 grains. Potassa is then an indispensable ele- 
ment, in a less degree however than phosphate of lime, 
since its absence does not, as with the preceding, cause 
the death of the plants. 

Seeing that soda replaces potassa in most industrial 
uses, we inquire if it might not do the same with re- 
spect to vegetation. Experiment has defeated this hope. 
In the absence of potassa, soda exercises no influence 
upon the yield, which remains just the same, whether 
it intervenes or not. It is then indisputable that, with 
regard to wheat, potassa is of the first necessity, and 
that soda cannot be substituted for it. 

It remains to explain the part played by lime. Here 
the question becomes much more complicated. The 
method we employed just now, and in which we made 
only pure and artificial products to enter, leads us to 
results of little importance only. 

An experiment made with nitrogenous matter, phos- 
phate of lime, and potassa only, gave a crop of 340 
grains, while we obtain 370 grains with the complete 
manure, by which I understand — the mixture of nitro- 
genous matter and the three essential minerals : phos- 
phate of lime, potassa and lime. This slight difference 
seems to indicate that lime plays only a secondary part. 
Nevertheless, agricultural practice obtains very good 



42 



effects from it. We must then seek by other ways to 
discover what may be the nature of its action. 

If wo substitute a mixture of sand and humus, for 
pure sand without lime, the yield remains, like the 
preceding, equal to 340 grains. In the absence of 
lime, the humus has, then, no action, either useful or 
injurious. But if we add lime (in the state of carbon- 
ate) in this same experiment, the yield immediately 
rises to 493 grains. The lime which, in the absence 
of all organic matter, influences the yield in but an 
insignificant manner, manifests, on the contrary, a very 
decisive action in the presence of humus, which produ- 
ces no effect of itself, when alone. 

There exists, then, between lime and humus a remark- 
able relation of unity. All the experiments lead us to 
this final conclusion : that the soil, to produce plants, 
must contain, under an assimilable form, a nitrogenous 
matter, with phosphate of lime, potassa and lime, and 
that to insure the eflicacy of this latter, the presence of 
humus is indispensable. You will now comprehend, 
without difficulty, why agricultural experiments made 
upon soils more or less fertile have not led, <and cannot 
lead, to any general practical conclusion. 

Suppose that an agriculturist had the idea of adding 
to a field abounding with phosphate of lime, a manure 
containing a mixture of nitrogenous matter, potassa and 
lime, he will obtain a magnificant harvest, — because the 
phosphate of lime in the soil united to the matters 
brought by the manure, will complete the latter, and 



43 



the plants will find every thing necessary to secure their 
development. 

This agriculturist will sound the praises of his ma- 
nure. Others, imitating his example, will try the same 
experiment. But if it happens that their fields contain 
no phosphate of lime, far from yielding the marvellous 
results promised, this manure will, on the contrary, 
lower the yield, for we now know that in the absence 
of phosphate of lime, a mixture of nitrogenous matter, 
potassa, and lime, is injurious to vegetation. 

This example will, I think, suffice to explain all the 
mistakes that cultivators have experienced in the course 
of agricultural experiments, and to justify my method, 
which consists of removing every thing unknown from 
the soil, by substituting for the latter an artificial mix- 
ture of definite composition. 

Now that by delicate and precise experiments we have 
arrived at the knowledge of the superior laws of the 
production of vegetables, shall we remain contented 
with philosophically contemplating them, and continue 
to follow, as before, a blind empirical practice ? Shall 
we continue without concern to exhaust the soil around 
us, and restore to it, in the form of manure, only a 
small portion of what it yields to us in the form of 
crops, ready to transfer our industry elsewhere, when 
our country refuses to nourish us, as the Arab transfers 
his tent and his flocks ? Or shall we continue, in de- 
spair of the cause, to surrender ourselves blindfolded 
to the charlatanism of adulterated manures and the 



44 



traders in an agricultural panacea ? No ! these truths, 
so simple and so fruitful, will quit our laboratories to 
enter into daily practice. Our industry will seek the 
elements of fertility in the vast quarries where nature 
has stored them up, and agriculture, henceforth, confi- 
dent in itself and its products, will assume greater 
attractions, and come to range itself, like all other 
branches of production, under the essentially progres- 
sive banner of supply and demand. 

Such is the prospect opened by science to agriculture, 
and which it remains for us to sound the depths. But 
before attempting, with reference to arable land, the 
problem we propose to solve under ideal conditions, we 
must study the soil itself, and learn how to ascertain its 
elements of fertility, in a word, to analyze it. In my 
next lecture I shall explain to you why chemists have 
failed, and shall show you how, more fortunate than my 
predecessors, I have arrived at success myself. 



ANALYSIS. 



SCIENCE CHIEFLY CONCERNS ITSELF WITH THE ELEMENTS OF 
BODIES AS MODIFIED BY ASSOCIATION, AND THE VARIOUS FORMS OF 
WHICH THIS ASSOCIATION IS SUSCEPTIBLE. — CHEMICAL ANALYSIS 
INADEQUATE TO THE ANALYSIS OF SOILS IN DISCOVERING THE 
CAUSES OF FERTILITY. — THE SYNTHETIC METHOD TEACHES THAT 
ANALYSIS NEED CONCERN ITSELF WITH FOUR ELEMENTS ONLY. — 
THE SOIL CONSISTS OF MECHANICAL AND ASSIMILBLE AGENTS, THE 
LATTER BEING ORGANIC AND MINERAL.— REVIEW OF THE ANA- 
LYTICAL LABOURS OF CHEMISTS; CAUSES OF THEIR FAILURE. — THE 
THREE MOST IMPORTANT QUESTIONS REMAINED UNSOLVED — " HOW 
MUCH WHEAT WILL A GIVEN SOIL PRODUCE?" " WHAT WILL BE 
THE BEST MANURE FOR IT, AND HOW MUCH MUST BE EMPLOYED?" 
" HOW LONG WILL ITS EFFECTS CONTINUE ?" — THE ELEMENTS OF 
FERTILITY IN A SOIL MUST EXIST IN AN ASSIMILABLE FORM, SO THAT 
WATER CAN DISSOLVE THEM AND CONVEY THEM TO THE INTERIOR 
OF THE PLANT THROUGH THE SPONGIOLES OF THE ROOTS. — THE 
BEST RE-AGENT IN ANALYSING SOILS IS THE PLANT ITSELF, AS IS 
SHOWN BY THE RESULT TO THE CROPS OF SUPPRESSING ONE OF THE 
FOUR ESSENTIAL FERTILIZING AGENTS. — THIS NEW METHOD BAN- 
ISHES ALL HYPOTHESIS, AND ADAPTS ITSELF TO EVERY WANT OF 
CULTIVATION. — RESULT OF EXPERIMENTS. 

45 



LECTURE FOURTH. 



Since chemical analysis has arrived at the discovery 
of the composition of most of the materials that render 
service to mankind, science has become accustomed to 
regard among the properties of bodies only that of 
their elements modified by association, and the various 
forms of which this association is susceptible. 

This theoretical view is more and more vcrioed in 
proportion as chemistry penetrates deeper into the 
study of nature : so much so that, now-a-days, the 
idea of the chemical elements, such as proceeded from 
the researches of the immortal Lavoisier, governs all 
the sciences which are occupied with matter and its 
transformations. The science of vegetation cannot 
rema : n a stranger to this movement, and the attempts 
directed to the end of bringing it under the common 
law have not failed. No sooner had chemical analysis 
begun to assume a scientific character, than it attempted 
to discover in the soil the causes of its fertility. But, 
too weak as yet to accomplish such a task, it exhausted 
itself in impotent efforts, and we may say that, notwith- 
standing the progress which has brought this young 

46 



47 



science rapidly to the maturity we witness at the pres- 
ent day, it has none the less remained unfruitful with 
regard to agricultural problems. 

The reason of this is very plain. Suppose we require 
of a chemist the analysis of a mineral containing traces 
of gold, without informing him of the presence of this 
precious metal in it. His attention will be given to 
each of the predominating elements ; as for the gold, 
it will escape his researches^ If, on the contrary, you 
point out to him the element you desire to prove the 
presence and quantity of, the chemist will proceed quite 
differently. He will begin by removing from his analy- 
sis all unimportant substances. Concerning himself 
only with the gold you have named to him, he will suc- 
ceed in concentrating it in a very small quantity of 
matter, where its presence will be manifested and its 
determination easy. 

When engaged in the analysis of soils, chemists 
have hitherto found themselves in the first of these 
two alternatives. Ignorant of what the elements of 
the soil were which played an important part in the 
formation of vegetables, they attributed this faculty to 
the agents which predominated in the soil examined. 
The direction of their analyses thus varied according 
to the various hypotheses which led them to a more or 
less happy intuition, or to the assertions more or less 
well founded of agriculturists. 

To change this state of things, we must substitute 



48 



for these hypotheses a certain knowledge which indi- 
cates, with absolute precision and rigor, the elements 
which analysis must occupy itself with, and if you will 
call to mind the facts established at the last lecture, 
you will have no difficulty in admitting that this knowl- 
edge is at the present time in a very promising condi- 
tion. 

For we know that there exists in the soil materials 
which do not enter into vegetable production except as 
a support to the roots, thus realizing a kind of recipi- 
ent for the useful elements. We designate them by 
the name of mechanical agents. 

We call assimilable agents all those which, at a given 
moment, penetrate the plant in the state of aqueous 
solution, to form afterwards an integral part of its tis- 
sues. 

Lastly, we rank in a third class the assimilable agents 
in reserve, all the organic and mineral debris which 
contain useful elements, but which cannot give them 
up to water until after a previous decomposition. 

We are thus led to the following classification of the 
elements of the soil, a truly natural classification, as it 
rests upon the facts which we have derived from the 
results of cultivation itself. 



49 



COMPOSITION OF A FERTILE SOIL. 



rSand. 

Mechanical agents -j Clay. 

' ( Gravel. 



Active assimi- 
lable agents. " 



3. Assimilable 



( Humus. 
Organic -< Nitrates. 

( Ammoniacal Salts. 
\ Potassa. 
Soda, 
Lime. 
Magnesia. 
Soluble Silica. 
Mineral 1 Sulphuric Acid. 
Phosphoric Acid. 
Chlorine. 
Oxide of Iron. 
L Oxide of Manganese. 
\ Undecomposed organic matters. 



agents in reserve. \ Undecomposed fragments of rocks. 



It is by ignoring or mistaking this classification 
that the most skilful chemists have failed to arrive at 
any useful result. Still, it will not be uninteresting to 
pass their attempts in review. 

Sir Humphrey Davy, one of the greatest chemists 
England has produced, conceived the idea of submit- 
ting to analysis various soils celebrated for their fertility, 
hoping thus to arrive at the recognition of something 
common between them, some preponderating element 
to which their agricultural properties might legitimately 
be attributed. 

The following are the results at which he arrived : 



50 



X 


< < ^ $ w 








i "i >-n 




a> 


nips . . 
eat . . . 
y ferti' 
ygood 






a 


3i 




-d 


^ 


9 










CO 


e 














SS 












C 














P 














OR 














ffl 


























CO 




GO Ci C5 CO CS 


co e 


ZD 


CO 


O 


O CO Oi 


§ 8 


I-* 


CO 


o 


O CO CO 


a o 














00 














CO 


to 


•<! 


C5 


to 


'— 


©i 




-<I 


o 


*k 


CO 


~3 


to 


X 














> 






1— t 


1—1 






5 


Oi 


a 


*>. 


►* 


>-' 


CO 


►*»■ 


CO 


o 


CH> 


to 


CO 


a 














a 


Oi 






»— » 






^ 2. 


•<l 


o 


tn 


1— » 


~J 


*h 




os 


-<1 


C5 


to 




co 




























(5 












CO 

o 


2. p 
P S" 


M 


o 


t-» 




o 


M 




. 




• 


j; 






o 2,^ 


CO 


CO 


to 




CO 


to 














Bog 2 














pi- 


to 


1— « 


to 


rf* 


o 


CO 


p? 


~3 


Ift 


CO 


£- 


Oi 


o 




























co 














r a 


| 










o 


3 -^=r 




g 


g 


£ 


~ 




i 










c 




! 












8 



51 



By an inspection of this Table, we perceive how lit- 
tle experience confirms the views of this celebrated 
chemist. He only proved dissimilarities between all 
the soils examined, and yet all were fertile. 

How can such a failure be explained ? If Davy 
had been aware of the facts which I have explained 
to you at our previous lecture, and with that summary 
classification which has engaged our attention, it would 
have been easy for him to see that, in his analyses, he 
had taken no account of the agents which alone assure 
the fertility of the soil. He makes no mention of po- 
tassa, phosphate of lime, or nitrogenous matters, princi- 
ples without which production is impossible. Davy 
analyzed the ore, without concerning himself with the 
precious metal. But could it have been otherwise at 
the date of his labors ? Chemistry had then only 
just got out of its leading-strings, and possessed but 
very vague notions of the life of plants, the result of 
empirical observations which no rational union had yet 
arranged. 

Again, far from perceiving the true cause of Davy's 
want of success, the science of his day drew a very 
singular conclusion from his labors. It was thought 
that the elements of the soil had no influence upon its 
fertility, and that if it were desired to find a reason for 
its agricultural qualities it must be sought in the study 
of its physical properties. 

This false interpretation has not been without its 
advantage to science. It has caused the production of 



o2 



extensive works on the part of physicists, and particu- 
larly from Schubler, who specially applied himself to 
researches of this kind. 

The result was a profound knowledge of the mechani- 
cal properties of the dominant agents of the soil, prop- 
erties, the influence of which, although secondary, 
nevertheless merit a serious examination. 

The labors of the physicists were scarcely a whit 
happier than those of the chemists, and the problem 
remained intact in spite of these two series of attempts. 
As usually happens, after excessive contradictions, they 
next attempted to reconcile the two methods, and M. 
Berthier undertook analyses in which he endeavored to 
take account of both the physical properties and the 
chemical composition of soils. Here is an example. 

SOIL OF THE VINEYARDS OF POMARD (COTE D'OR). 

No. 1. No. 2. 

Quartz remaining upon the hair sieve 2.6 2.5 

Quartz remaining upon the silk sieve .... 1.4 2.0 

Quartz obtained by levigation 8.5 4.6 

Exceedingly fine quartz .... 17.5 13.3 

Comb.Hedsilex «!«*"" H\ «" 

Alumina 5.1) 3.9 J 

Hydrate of iron 9.8 7.4 

Calcareous stone remaining upon the hair 

sieve 23.0 38.5 

Ditto remaining upon the silk sieve 2.9 10.0 

Calcareous stone in fine grains 7.8 2.2 

„ ,, in exceedingly fine grains 11.3 7.8 

Organic matters 1 2.0 

101.1 - — 102.0 

After the labors of M. Berthier, science was not 



more advanced than before, and the most skilful 
chemist was still without a reply to the three ques- 
tions which interested agriculturists in the highest 
degree : — 

1. How much wheat will such a soil produce ? 

2. What will be the best manure for it, and how 
much must be employed ? 

3. How long will its effect continue ? 

Now-a-days science seems to have made a step. In- 
stead of contenting itself with measuring the mechani- 
cal elements of the soil, it determines, with the great- 
est care all the elements of fertility : lime, magnesia, 
the alkalies, phosphoric acid, nitrogen, &c, as, more- 
over, we may convince ourselves by the following 
example : — 

ANALYSIS OF A SOIL IN THE ENVIRONS OF 
CHALONS-SUR-MARNE. 



1 . Mechanical Analysis. 

Fine Matters 52.50 | Sand and Gravel 42.25 

2. Chemical Analysis. 

Lime 40.50 

Magnesia traces. 

Alkalies 0.38 



Organic matter 1.80 

Hygrometic moisture. . . 2.70 

Water of combination . . 5.92 

Carbonic acid 33.20 

Quartz sand 3.10 

Clay 6.00 

Attackable silica 3.10 

Oxide of iron 2.00 

Alumina 0.15 



Sulphuric acid 0.28 

Phosphoric acid 0.12 

Nitrogen and chlorine . . traces. 

99.25 



54 



But these laborious and complete analyses, in which 
nothing is forgotten, are still useless to agriculture, and 
cannot, any more than the preceding, reply to the 
questions that essentially concern it. 

In fact, for a soil to be fertile, it is not sufficient that 
it contains potassa, phosphoric acid, lime, and nitro- 
gen : these agents must also exist in an assimilable 
form ; that is to say, in a state in which the water in 
the soil can dissolve them, to convey them into the 
interior of plants through the spongioles of their 
roots. 

Suppose that a soil contains a feldspathic sand in- 
stead of a quartz sand. Chemical analysis would show 
the presence of all the agents useful to vegetation, and 
still this soil would be of a desolating sterility j for, in 
feldspar, these bodies are combined in silicates which 
water cannot dissolve. 

Not only, then, is it necessary to determine the 
presence and quantity of the useful elements, but 
analysis, to be fruitful, must also occupy itself with the 
kind of combinations in which they are engaged. I 
have myself sought the solution of the problem in this 
direction; and, to remove from the first attempt that 
portion of the soil which can contribute nothing to its 
fertility, I have commenced by washing the soil with 
distilled water, hoping to arrive, by evaporating the 
liquid obtained, at concentrating in a small bulk the 
only principles which it was necessary to take notice 
of. 



55 



Submitted to this treatment, the soil of Vincennes 
yielded to water only a very little potassa, and no 
phosphates at all. Nevertheless, three successive 
crops of wheat have extracted 1881bs. of phosphoric 
acid and 20361bs. of potassa. The exhaustion by dis- 
tilled water is therefore much less efficacious than the 
natural exhaustion. In fact, in the soil the solvent 
power of the water is greatly increased by the carbonic 
acid with which it is constantly charged by the salts it 
dissolves, and by the time during which it acts. 

With the view of approaching nearer to the condi- 
tions of solution in nature, I have attempted to exhaust 
the soil by water slightly acidulated with hydrochloric 
acid. But then I fell into the opposite extreme. 
While the three crops of wheat exhausted the soil and 
extracted from it only 1881bs. of phosphoric acid, 
acidulated water indicated lOOOlbs. the acre. In fact, 
chemistry has not been more powerful in my hands 
than in those of my predecessors, and the failure must 
be attributed to the insufficiency of the methods of 
exhaustion at command. 

Must we, then, despair of ever being able to analyze 
the soil in a brief space of time by means of a labora- 
tory susceptible of denning its agricultural properties 
with certainty? I do not think so. The problem, 
although not hitherto solved, does not appear to be in- 
soluble. The whole difficulty consists in extracting 
from the soil every thing that plants are susceptible of 
drawing from it, without going beyond what they do 
themselves. 



56 



Perhaps dialysis, from which Mr. Graham has de- 
rived such admirable results, may, by its application 
to the study of soils, lead to more useful data than 
those I have criticised. But these methods are not 
yet instituted, and I speak of them only as things 
hoped for. 

Leaving aside, then, the chemistry of the laboratory, 
the present weakness of which we fully recognize, and 
taking up the results I have previously explained to 
you, we deduce a more certain method, one in which 
we employ no other reagent than the plant itself. 

If you recall to mind what I said in our last lecture, 
you will remember that four essential agents suffice to 
assure the fertility of soils, and that the suppression of 
one of them lowers the yield to a very important ex- 
tent. Now, conceive a soil naturally provided with 
phosphates, is it not evident that the suppression of 
phosphates in the manure supplied to it will produce 
no bad effect ? Reciprocally, whenever the manure 
without phosphates produces a crop equal to that from 
a manure which does contain it, we shall be justified in 
admitting that the soil is naturally provided with it. 

Do you wish to be similarly instructed with regard 
to lime, potassa, and nitrogenous matter ? Cultivate 
the same soil with manure deficient in lime, potassa, 
and nitrogenous matter, and, according as they produce 
good or bad crops, draw your conclusions as to the 
presence or absence of these agents of fertility. 

This new method banishes all hypothesis, since it 



rests upon the following facts, proved by experience, 
namely : — 

1. That the association of minerals and an assimi- 
lable nitrogenous matter produces good crops every- 
where ; while isolated, these agents are always inert. 

2. That lime produces a useful effect only in pre- 
sence of humus. 

3. That lime and humus produce great effects only 
in a soil provided with minerals and nitrogenous mat- 
ter. 

This method adapts itself to all the wants of cultiva- 
tion, since it is sufficient to scatter a few handfuls of a 
fertilizing manure upon a field, to indicate, at the time 
of harvest, what the soil contains, what it wants, and, 
consequently, what must be added to it to render it 
fertile. 

Lastly, it is essentially practicable, as it requires no 
difficult manipulation, no apparatus, and employs only 
the usual processes of cultivation. 

It now remains for us to examine to what degree it 
is precise and exact, and with that to put it to the test 
of experiment. 

The following are the results obtained in three differ- 
ent soils, compared with those given by calcined sand 
under similar conditions. 



58 





1 


2 


Complete Manure. 


3 


4 


5 


6 


7 


Calcined 




"S3 

£3 


m 
O g ffl 

§g»s 


Without 
Phosphate 
of Lime. 


S3 

— Eg 

>0-i 


"3 .: 

o a 

E 3 


00 
















Sand. 


6 


24 


8 





7 


22 


32 


Soil from 
















Gascogne. 


55 


32 


9 


6 


8 


22 


" 


Soil from 
















Bretagne. 


4 


29 


16 


9 18 


f< 


** 


Soil of 
















Vincennes. 


11 


35 


20 


28 


28 


32 


" 



The soil from the landes of Gascogne, without ma- 
nure, was not more fertile than calcined sand: with 
complete manure, its yield was equal to that of calcined 
sand with humus and complete manure, this soil there- 
fore contained humus. 

Reasoning in the same manner with regard to the 
elements, we see that it contains neither nitrogenous 
matter, nor potassa, nor lime, since, in their absence, 
it is not more fertile than calcined sand. On the other 
hand, it contains traces of phosphoric acid, for in the 
I experiment where it was not added, it yielded a light 
crop, while in the sand the plants invariably perished. 

As for the soil of the landes of Bretagne, these ex- 



59 



periments show it contains humus, a little nitrogenous 
matter, a little potassa, and very small quantities of 
phosphates. 

The soil of Vincennes, examined in the same man- 
ner, showed itself to be rich in humus, phosphates, po- 
tassa and lime, but poor in nitrogenous matter. 

These are positive data, which we can employ in fer- 
tilizing soils. Let us now see to what extent they 
were verified in practice on a large scale. 



60 



r 



S. p 

3 3 



00 



oo 



Or CO 

00 O 

o o 



00 

O 



III 



O Or 

O O 



5 * 



o 

c 
2 

3 



13. S 



61 



This table shows that, without phosphates, the crop 
was nearly equal to what it was with a complete 
manure : that without potassa it sensibly diminished, 
and that without nitrogenous substances, it was very 
inferior. These results are exactly like those derived 
from experiments on a small scale. But do you wish 
to see with what precision these results agree ? Sup- 
pose the crop with complete manure equal to 35, as it 
was on the small scale, and calculate the others with 
reference to that. 

You will thus be led to the following comparison : 





Complete 
Manure. 


Complete Manure. 




Without 
Nitrogen 
Matter. 


Without Without 
Potassa. Phosphates. 


Cultivation on 








small scale. 


35 


20 


28 28 


Cultivation on 








large scale. 


35 


21.7 


30 32 



I will ask you, is it possible to attain to a more 
perfect concordance, and is it not the most satisfactory 
proof of the excellence of the method I have com- 
municated to you ? 

The plant therefore becomes in our hands one of 
the most perfect instruments of analysis, the only one, 
in the present state of science, susceptible of making 
known, practically, the composition of soils. But I 
shall give to this proposition a still more striking 



62 



demonstration, by snowing you to what extent this 
test goes. 

We have seen that, in calcined sand and complete 
manure without phosphates, we succeed in causing the 
death of plants. In the soil from the landes of Gras- 
cogne the same compound gave a crop equal to 6, 
which proves, as we have stated, the presence of small 
quantities of phosphates in the soil. 

To lcwt. of calcined sand and complete manure 
without phosphates, add only T £^ of 1 per 100 of 
phosphate of lime, that is to say, y^oiro of tne 
weight of the soil. Immediately the yield rises to 6, 
as in the soil of the landes of Glascogne. 

We are then correct in saying that vegetation re- 
veals to us with certainty, in this soil, the presence 
of T ooVoo of phosphate of lime. 

What chemical process, let me ask, can attain to 
such limits ? 

The accuracy of this method, in relation to the 
other elements, is no less remarkable. ti^ti °f 
potassa cause the yield to pass from 8 to 32 : tw ^q <y 
of lime in presence of humus raises it from 12 to 24. 

We are then assuredly in possession of a means of 
analysis, the perfection of which yields in no respect 
to the most delicate processes of the chemical labora- 
tory, the indications of which are verified exactly by 
cultivation on a large scale, capable, consequently, of 
throwing a sure light upon agricultural operations. 

To put it into practice, the agriculturist will only 



63 



have to reserve some square plots in a field, to.which 
he will give complete and partial manures of the fol- 
lowing composition for the surface of an acre : 



Phosphate of Lime 

Carbonate of Potassa 

Quick Lime 

Nitrate of Soda, (nitroge- 
nous matter) 



lbs. 
352 

352 

132 

488 






lbs. 
352 



352 
132 



a ~ 



lbs. 
352 



488 



132 



488 



II 

£| 

Ph 

IbsT 



352 
132 



488 






lbs. 
352 



352 



488 



At the harvest he will carefully note the results ob- 
tained, and for the following year he will fix upon that 
which his soil requires, and, consequently, upon that 
which he must give to it to restore its original fertility, 
and to fertilize all the plots, if they do not give good 
results. 

For several years past, geologists have endeavored 
to prepare maps in which they represented, by particu- 
lar tints, soils of different geological construction. 
These maps assumed to come to the aid of the agri- 
culturist, but they completely failed, like the method 
of analysis upon which they were founded. By the 
processes I have explained to you, we can now ascer- 
tain the real agricultural properties of soils, and conse- 
quently resume the task of the geologists with the aid 
of data from cultivation itself. We shall in this man- 



64 



ner arrive at constructing true agricultural maps. 
What is required? Some experimental fields anal- 
ogous to those at Vincennes, disseminated over the 
surface of France, upon lands belonging to the princi- 
pal geological types. The centralization of the results 
obtained will permit of the drawing up of an exact 
inventory of the agricultural resources of the Empire. 
To give you some idea of the benefit which may be 
derived in this object, from our own method, it will 
be sufficient for me to compare the results of the farm 
at Vincennes with those obtained in England by 
Messrs. Laws and Gilbert, who also have instituted, 
at their farm at Rothamstead, experiments in cultiva- 
tion with manures of known composition. 

MESSRS. LAW & GILBERT'S RESULTS. 



Years. 


Complete 
Manure. 


Minerals without 

Nitrogenous 

Matters. 


Nitrogenous 

Matters 

with Minerals. 


( Straw 
1855 -j 

( Grain 


lbs. 
9,656) 

Y 14,386 
4,730) 


lbs. 
4,426 ) 

Y 8,342 
3,916) 


lbs. 
6,06 7) 

}■ 13,925 
7,858) 


( Straw 
1856 1 


9,480) 

Y 14,420 


5,060) 

[ 8,012 
2,952) 


3,916) 

V 11,629 


( Grain j 4,940 ) 


7,713) 


( Straw 

1857^ 

( Grain 


9,460) 

}■ 16,230 
6.770) 


4,100) 

[■ 7,670 
3,570^ 


4,196) 

}■ 11,496 
7,300 ) 


Mean . . 


15,010 


10,208 12,324 



65 

RESULTS AT VINCENNES 
Mean 17.992 10.57 12.824 

With complete manure the mean yield is nearly the 
same, without nitrogenous matter the yield at E-otham- 
stead is very inferior. Messrs. Laws and Gilbert's 
land therefore contains less nitrogenous matter than 
that of Vincennes. 

Without minerals, the yields are very nearly alike, 
the two soils have therefore nearly the same mineral 
richness. There is a slight advantage for that of 
Vincennes. 

Thus you perceive that, armed with our method, we 
can make a retrospective analysis of all the soils of 
which we possess information of the exact culture. 
Still better when the documents collected for the pur- 
pose are as complete as possible. 

But it will not be sufficient to point out to you the 
agents by means of which we can analyze the soil and 
fertilize it. To give you the power to manage these 
valuable fertilizers, I must also tell you under what 
form they must be administered to plants, and from 
what sources of human industry they can be provided. 
This will form the subject of my next lecture. 



ANALYSIS. 



THE IDEAL MANURE, OR MANURE par excellence. — COMPARISON 
BETWEEN THE COMPOSITION OF IDEAL AND PRACTICAL MANURE. 

— definition of nitrogenous matter. — sources from whence 

NITEATKS MAY BE OBTAINED.— FROM THE ATMOSPHERE: FROM TDK 
AMMONIACAL SALTS OBTAINED IN COAL-GAS MANUFACTCRE \ FROM 
SEWAGE WATERS. — THE HYDROCHLORATE THE BEST FORM OF AM- 
MONIA TO BE EMPLOYED. — VALUE OF NITRATE OF POTASSA, AND 
OF NITRATE OF SODA. — ANIMAL AND VEGETABLE REFUSE A SOURCE 
OF NITROGEN. — THE PHOSPHATES; IN CHALK, NODULES, COPRO- 
LITES, APATITE, OSSEOUS BRECCIA, SUGAR REFINER'S CHARCOAL, 
BONES, GUANO. — PHOSPHATE OF LIME. — POTASSA, NITRATE, CAR- 
BONATE.— NEW SOURCES FOR THE SUPPLY OF POTASSA, FROM SEA 
WATER AND FELSPARS. 



LECTURE FIFTH. 



I have announced to you for to-day's lecture, the 
particular study of the agents we can employ to fer- 
tilize or analyze the soil. But before entering upon 
details, it is necessary to note the point at which we 

66 



G7 



have arrived, and to explain to you the idea of manure 
such as it is when disengaged from the principles I 
have previously laid down. 

We have shown that the fertility of soils depends 
on the presence, in their suhstance, of the elements 
which we have called active assimilable agents. From 
this it evidently results that, to render a barren soil 
fertile, it will suffice, in most cases, to add the whole of 
these elements to it. This is, in fact, what the experi- 
ment with calcined sand proves, where such a mixture 
realizes conditions of fertility equivalent to those of a 
good soil. We may say, then, that this mixture is the 
ideal mixture, the manure par excellence. 

But when we work upon arable land, it is impossible 
that it should not already contain a portion of the 
necessary elements. Some, such as iron and man- 
ganese, of which plants take up only infinitesimal 
quantities, exist almost everywhere. Generally, then, 
there need be no fear of their deficiency. We may 
therefore dispense with introducing them into a prac- 
tical manure. 

We also banish from its composition all the agents 
of which the mode of action is only imperfectly 
known to us, or in which we are still ignorant of the 
form susceptible of manifesting their influence. It is 
for this reason that we exclude soda, magnesia, sul- 
phuric acid, and chlorine. 

Science, from its nature, is essentially progressive, 
and I do not pretend that I possess the whole truth, or 
that nothing remains to be discovered. Far from this, 



68 



I hope, on the contrary, I may be permitted to add 
fresh knowledge to that which I have already imparted 
to you, and it is with this aim that I actively pursue 
my researches. Let us then banish every exclusive 
idea, and construct a manure as perfect as the science 
from which it is deduced, and content ourselves with 
composing it of elements, the action of which is wholly 
definite, the useful form perfectly known, and of which 
plants require important quantities. This practical 
manure will represent all that we can obtain most per- 
fect in the present state of our knowledge, it will be 
sufficient in the generality of cases for all the require- 
ments of cultivation, and if the future be called to 
make useful additions, we can at least assert that we 
shall have nothing to retract. 

These considerations leads us to the conclusions ex- 
pressed in the following table. 





r 


Ideal Manure. 

Humus. 


Practical Manure. 




; 


Nitrates. 


j Nitrogenous 




Organic 


Ammoniacal Salts. 


( matter. 






Potassa. 


Potassa. 


Active Assimi- 
lable Agents. 




Soda. 
Lime. 
Magnesia. 
Soluble Silica. 


Lime. 




Mineral. 


Sulphuric Acid. 
Phosphoric Acid. 
Chlorine. 


Phosphate. 






Oxide of Iron. 
Oxide of Manganse* 





69 



Among the constituents of the practical manure 
figures lime, which is easily procured everywhere, and 
with the history of which nearly everybody is ac- 
quainted. I may therefore dispense with repeating it 
to you, preferring to reserve my explanations for less 
known materials, and which it is less easy to obtain. 

I call nitrogenous matter every principle which in- 
cludes nitrogen among the number of its elements, and 
capable of supplying it to vegetation. This includes 
the remains of all beings that have lived. Buried in 
the soil, they undergo slow decomposition, in conse- 
quence of which their nitrogen separates partly in the 
state of carbonate of ammonia or of nitric acid. These 
substances are retained in the soil by humus or by 
clay, and water afterwards dissolves them gradually 
and conveys them into the interior of vegetables. But, 
as nitrogenous matters of animal or vegetable origin 
are useful only after being transformed into ammoniacal 
salts or nitrates, there is every advantage in having 
recourse to these products ; this is why, from the 
present point of view, we give them also, by extension, 
the denomination of nitrogenous matters. 

I have already shown you the efficacy of the nitrates 
and of the ammoniacal salts, in our second lecture, and 
I need not return to the subject, but limit myself to 
making known to you the sources from whence we 
may obtain these compounds. 

The great natural store of nitrogen is the atmos- 
phere. We have seen that vegetation in general en- 



70. 



joys the faculty of drawing from it the greater portion 
of the nitrogen it assimilates. The idea of imitating 
nature, and of procuring nitrogenous compounds by 
causing the nitrogen of the air to enter into combina- 
tion, has for a long time presented itself to the minds 
of chemists. Unfortunately, free nitrogen possesses 
only very feeble affinities, which renders the problem 
thus put by chemistry extremely difficult of solution. 
Recently, however, Messrs. Sourdeval and Margueritte 
have succeeded in producing ammonia with the nitro, 
gen of the air by a very interesting reaction, but still 
too expensive for it ever to become an important source. 
These chemists made atmospheric nitrogen pass over 
carbon impregnated with baryta, at a very high tem- 
perature. In this manner cyanide of barium Ba C 2 N 
is produced, the nitrogen of which is converted into 
ammonia by a current of steam from water. This 
remarkable experiment realizes the scientific solution 
of the problem, but it does not give the economic 
solution. 

For many years past the manufacture of coal gas 
has thrown very important quantities of ammoniacal 
salts into commerce. We know that coal contains 75 
per 100 of nitrogen, which is partially disengaged 
during its distillation. This ammonia is condensed in 
acid waters, the evaporation of which furnishes am- 
moniacal salts. This course is certainly not to be 
despised, but it is far from being sufficient. 

England consumes annually 1,000,000 tons of coal 



71 



in the manufacture of gas. From this results about 
10,000 tons of ammoniacal salts, which scarcely suffices 
to supply 50,000 acres of arable land with nitrogenous 
manure. If we remember that the territory of France 
contains about 125,000,000 acres of cultivated land, 
we shall have an idea of the importance of the outlet 
which agriculture presents to ammoniacal salts, and of 
the insufficiency of gas manufacture to supply this 
consumption. It must not be forgotten, however, that 
this is a source scarcely turned to full account, which 
rests upon a manufacture very rich in its future 
promise, and which would receive important develop- 
ments if the production of coke in closed chambers 
were generally substituted for its manufacture under 
the open sky. 

The ammoniacal salts arising from the distillation of 
coal merit, besides, all our sympathies, for they restore 
to the vegetation of our times a portion of the nitrogen 
which has contributed in former times to the immense 
vegetable formations of which coal presents us the 
debris. They thus place at the disposal of human 
industry considerable quantities of combined nitrogen, 
which, in this manufacture, remain entirely lost, buried 
in the bowels of the earth. 

There exists another very abundant source of am- 
monia : in sewage waters. These waters have for a 
long Jime been the object of a certain manufacture. 
They are distilled with lime in large leaden retorts. 

The ammonia disengaged is collected in diluted hy- 



72 



drochloric acid, the evaporation of which yields sal 
ammoniac. But the heat lost at the end of each opera- 
tion raises the cost of this product too high for the 
manufacture to become extensive. Messrs. Sourdeval 
and Margueritte have recently applied to this distilla- 
tion a continuous apparatus similar to that which ren- 
ders such great service in the manufacture of alcohol. 
By this happy innovation the cost of production has 
been greatly reduced, and these gentlemen, in a single 
manufactory, have already succeeded in manufacturing 
about 6 tons of sal ammoniac per day, which they sell 
at a very moderate price. This manufacture, which is 
susceptible of very great extension, may become a 
source of wealth to agriculture, for it will permit of 
returning to it a great portion of the combined nitro- 
gen, which it continually withdraws in the form of 
crops, and which thus accumulates in cities, where it 
is generally lost, to the great detriment of the public 
health. 

Whatever be the source of the ammonia, its hydro- 
chlorate (N H 4 CI) appears to be the most advan- 
tageous form under which it can be employed. It has 
always given us good results. To light lands it may 
be given in quantities of 44Glbs., representing 1141bs. 



01 



nitrogen, per acre. But upon strong lands this 
quantity would be excessive, unless the season was 
wet : it would cause the wheat to be laid. In such 
cases, we must reduce it to 260 or 3001bs. at the most, 
which, at the rate of 17 shillings the cwt., makes a 



73 



manure of 37s. to 47s. In sal ammoniac, nitrogen 
costs Sd. per pound. 

Instead of this salt, we can employ Peruvian nitrate 
of soda, the price of which is also 17 shillings the 
cwt. Only, as it contains less nitrogen than sal am- 
moniac, it is dearer. The cost of its nitrogen is about 
Is. per lb. Whenever, then, it is proposed to give 
nitrogenous matter only to the soil, it is best to have 
recourse to sal ammoniac. But when we wish to make 
it enter into a mixture constituting a complete manure, 
and consequently containing lime, a mixture which 
may be kept and sent to a distance, then it is prefer- 
able to take nitrate of soda, because, under the influ- 
ence of moisture, lime in time decomposes the sal 
ammoniac, and thus causes the loss of a portion of the 
useful nitrogen. 

To employ nitrate of soda, it suffices to scatter it on 
the soil, the same way as seed, and afterwards harrow 
it in, so as to mix it well with the upper layer of the 
soil. With sal ammoniac it is preferable to first mix it 
with two or three times its weight of moist earth, 
then leave it to dry, and spread it afterwards. By this 
method its diffusion is very uniform. 

To give nitrogen to the crops, we can also, besides 
nitrates and ammoniacal salts, have recourse to all nitro- 
genous matters of animal or vegetable origin which can 
be procured economically, provided they are readily 
decomposed in the substance of arable land, without 
which their useful effect maybe wasted for a long time. 



74 



In the employment of these matters we must also take 
into account, that only about one-third of their nitro- 
gen, separated during their decomposition to the ele- 
mentary state, can be profitable to vegetation as com- 
bined nitrogen. 

Let us now proceed to the study of the phosphates. 

Phosphoric acid is widely diffused in nature : it ex- 
ists in very small proportions in most of the crystalline 
rocks, where it is in combination with alumina and ox- 
ide of iron. In this state it is useless to vegetation, as 
water cannot dissolve it. In the sedimentary soils, it 
presents itself, on the contrary, under a form essentially 
assimilable to that of phosphate of lime. But in gen- 
eral, the soil contains only traces of it, some ten thou- 
sandths at the most, and in many countries where cul- 
tivation has been long continued, the soil has become 
wholly exhausted of it. Fortunately, there exists upon 
certain points of the globe, considerable quarries of it, 
sufficiently abundant to repair the losses of the past 
and secure the wealth of the future. 

Chalky which forms such immense deposits, always 
contains phosphate of lime, — the proportion is much 
greater the deeper we descend. At the base of the 
cretaceous strata a peculiar mineral is met with, in 
fragments of various sizes, which contain as much as 
50 per cent, of phosphate of lime. 

This product, which is very abundant, has been re- 
cently discovered j it is known under the name of nod- 
ules, and promises to yield an inexhaustible supply to 



75 

agriculture. But there is another quite as extensive, 
and much richer, and very easily worked : this is apa- 
tite, which, in Spain, forms entire mountains, and can 
be taken from the surface by the simplest means. Apa- 
tite is a combination of tribasic phosphate of lime with 
an equivalent of fluoride of calcium, 3 Ca PO 6 + 
Ca Fl. In this state the phosphate of lime is very as- 
similable, but it is easy to disaggregate this rock and 
render it accessible to vegetation. It is only necessary, 
after reducing it to powder, to sprinkle it with its 
weight of sulphuric acid diluted with an equal volume 
of water. Sulphate of lime is thus produced, and acid 
phosphate of lime, which is very soluble in water. 

We can treat in the same manner the nodules and in 
general the tribasic phosphate of lime, whatever its 
origin. The acid phosphate encountering an excess of 
carbonate of lime in the soil, passes to the state of neu- 
tral phosphate, which is a condition most favorable to 
its absorption by plants. 

Before the discovery of the nodules which begin to 
enter largely into practical agriculture, and of apatite, 
which has only recently made its appearance, we have 
had recourse, successively, to coprolites, a sort of phos- 
phated concretion of animal origin, abundant quarries 
of which exist ; to the fossil bones found in caverns, 
and in rocks known as osseous breccia : to the charcoal 
black of sugar refineries, and also to the bones in a 
natural state, after calcination, or after a previous boil- 
ing to remove the fat, which are infinitely superior. 



76 



All these products have rendered, and can still render 
great service, but there is another to which I desire 
more particularly to call your attention, both on account 
of the important part it has played in the agricultural 
revolution we have witnessed, as in consideration of its 
richness in phosphates, and of the abundance of its 
sources. This is guano. 

When this product began to be noticed about 1804, 
no one then supposed that it was possible to find a sub- 
stitute for the farm dung-hill. It was this that at- 
tracted the attention of chemists and agriculturists to 
artificial manures, and such was the state of ignorance 
that continued to prevail till within a few years that the 
fertilizing properties of guano were exclusively attrib- 
uted to the nitrogen it contained. Whatever ideas 
were entertained of its action, the good results it pro- 
duced, showed, also for the first time, that it was possi- 
ble to obtain very good crops by processes that finally 
broke up the traditions of the past, and opened to ag- 
riculture the entirely new path of artificial manure. 

Guano forms extensive deposits upon the islands 
scattered in the Pacific ocean, and upon the coast of 
Peru. It is supposed to be produced by the excre- 
ments of birds that feed upon fish. Its composition is 
not quite favorable to this hypothesis. It contains 
much more phosphoric acid, proportionally, than the 
excrements of birds. It therefore seems to me more prob- 
able that it contains both the excrements and the skele- 
tons of birds. Whatever it be, guano containing both ni- 



trogen and assimilable phosphate of lime, constitutes 
an essentially fertilizing substance. To convert it into 
a complete manure, it is sufficient to add to it potassa 
and lime. Guanos are not always of the same compo- 
sition. Their richness in nitrogen varies from 5 to 14 
per cent., and their contents in phosphates extend to 
25 or 35 per 100. Therefore, before employing these 
products, it is necessary to submit them to analysis, 
both to guard against adulteration, to which they are 
frequently exposed, and to ascertain the quantities that 
should be employed. 

Whatever the form under which we obtain phosphate 
of lime, the proper quantity per acre is 1601bs. We 
can previously convert it into phosphoric acid, as I be- 
fore stated, and then begin by mixing it with two or 
three times its weight of earth, leaving it to dry, and 
afterwards spread it over the soil. We can thus em- 
ploy it direct, but in this case it is important to dis- 
tinguish that which is assimilable from that which is 
not. Thus, apatite can never be turned to account in this 
manner, for, notwithstanding the 80 per 100 of phos- 
phate of lime it contains, its effects will be very doubt- 
ful. 

Hitherto the acid phosphate has been employed ex- 
clusively in England. In France, on the contrary, it is 
the direct employment which has prevailed. But I 
have no doubt that our agriculturists will ultimately 
imitate our neighbours in this point, which seems to me 
to be the wiser plan. 



78 



In our practical manure we have included a fourth 
element, potassa : it remains for me to give you its 
history. 

I have previously shown you the necessity for its 
presence in the soil, and the impossibility of substitut- 
ing soda for it, which has now replaced it in most man- 
ufacturing processes. With manure, substitutions are 
impossible, for each principle has distinct and exclusive 
properties. The vegetable is a reagent, which distin- 
guishes the slightest shades of difference. You will 
have a fresh proof of this on studying the form under 
which the potassa has most efficacy. Chloride of potas- 
sium, sulphate of potassa, and the carbonate of the 
same base, are all three soluble in water ; all three are 
absorbed by the roots ; yet the chloride is completely 
inactive, the sulphate produces only an insignificant ef- 
fect, and the carbonate gives the best results. We also 
obtain excellent effects with silicate of potassa contain- 
ing sufficient silica to prevent its being attacked by wa- 
ter, except very slowly. It is under this form that I 
have always employed potassa in my experiments on a 
small scale. This salt possesses the advantage of fur- 
nishing that alkali, in proportion, so to speak, to the 
wants of the plant. But its employment on the large 
scale is impossible, because its price is much too high. 
Besides, it acts only after being converted into carbo- 
nate under the influence of the carbonic acid in the 
soil. It is therefore preferable to have direct recourse 
to carbonate of potassa, which is both the most active 



79 

and the most economical form under which this agent 
can be procured. 

There is, however, another salt, which would be much 
more advantageous if it could be obtained at a low 
p r i ce __ viz. nitrate of potassa. It contains, at the 
same time, 50 per 100 potassa and 14 per 100 nitrogen, 
both eminently assimilable j so that, mixed with phos- 
phate of lime and lime, it constitutes a complete ma- 
nure. 

Unfortunately, its price is now 51s. per. cwt. If we 
reckon the 15^1bs. of nitrogen it contains at 15c?., 
there still remains nearly 34s. for the 561bs. of potassa, 
which makes 68s. for 1121bs., while in its other com- 
pounds it costs only 42s Qd. per. cwt. Still, I have 
thought it my duty to point out to you the advantages 
of nitrate of potassa, which contains upwards of 60 
per 100 of assimilable matter, in order to stimulate 
chemists to seek the means of producing it economi- 
cally. 

The sources of potassa are not very numerous. For 
several years past, all that has been found in commerce 
was obtained by washing the ashes of plants. America 
and Russia have for a long time been the principal 
sources of supply; and it was an excellent thing — 
that the wild desert should be impoverished to enrich 
the industry of civilized countries 

Along with the potashes of Russia and America, 
that obtained in the manufacture of sugar from beet- 
root has of late years been placed. This plant, in fact, 



80 



draws from the soil considerable quantities of potassa, 
which is found in the residues of its distillation, or in 
the molasses which remains after the crystallization of 
its sugar. It is only necessary to evaporate the wash, 
and calcine the residue, in order to obtain the carbo- 
nate of potassa. 

This manufacture has rapidly taken a great develop- 
ment, and yields large profits to those engaged in it : 
but it ruins the soil in which the beetroot is grown. 

Twenty years ago, the beetroot grown in the neigh- 
borhood of Lille gave a juice very rich in saccharine 
matter ; at the present day, notwithstanding the addi- 
tion of abundance of manure, and the application of 
the most perfect system of cultivation, a juice contain- 
ing more than 5 or 6 per 100 cannot be obtained, con- 
sequently it is only available as food for cattle. The 
reason of this is very plain : the manures employed 
restore to the soil only very small quantities of potassa, 
insufficient to repair the losses caused by the abundant 
exportation just alluded to. 

If the agriculturist desires to restore sugar to his 
beetroot, he must supply the soil with potassa. But 
then he will have to sacrifice the greater part of the 
capital he has derived from the sale of the potassa in 
former years. 

Fortunately, new sources of a supply of potassa are 
growing up, and I have every reason to believe that 
agriculture will soon be supplied with it at a low price. 

I shall first mention the extraction of potassa from grea- 



81 



sy wool, a branch of industry newly created by Messrs. 
Maumene and Rogele\ These gentlemen collect the 
waters of the first washing of the fleece before dyeing it, 
evaporate them in large vats, and calcine the residue in 
gas retorts. They thus obtain a very brilliant gas, and 
as a residue crude carbonate of potassa, which is left 
in the retorts. 

This is a very interesting source, as it returns to the 
service of industry a quantity of potassa which, hitherto, 
was absolutely lost. But it is not susceptible of a very 
great extension, and, in fact, it is still from the potassa 
derived from agriculture that the return to the soil will 
serve, in a certain measure, to maintain its fertility; 
but we cannot, in any way, raise its power of produc- 
tion. 

There is still another manufacture which promises, 
at some future day, to reduce the price of the salts of 
potassa. 

Formerly, in the manufacture of sea salt, the mother- 
waters were cast into the sea. 

M. Balard, by patient and laborious studies, has suc- 
ceeded in showing that these mother-waters may be 
made to yield several useful salts at little expense. 

M. Balard's processes, modified by M. Merle, who is 
established at Camargue, operate on a very large scale, 
and produce considerable quantities of chloride of po- 
tassium. 

Sea water is submitted to a first evaporation in the 
sun, in consequence of which it deposits four-fifths of 
6 



82 



its chloride of sodium. The mother-waters are then 
removed to special reservoirs, where they are suddenly 
cooled to 32 degrees below freezing point by M. Carre's 
ice-making machine. At this low temperature double 
decomposition takes place between the remaining chlo- 
ride of sodium and the sulphate of magnesia, from 
which results sulphate of soda, which crystallizes, and 
chloride of magnesium, which remains in solution. 
After the removal of the sulphate of soda the mother- 
water contains only chloride of magnesium and chlo- 
ride of potassium, which are made to deposit by a fresh 
refrigeration in appropriate vessels. A washing after- 
wards removes the chloride of magnesium, and leaves 
the much less soluble chloride of potassium almost in 
a state of purity. 

I have visited M. Merle's establishment, and I can 
assure you that it is an exciting spectacle to see these 
immense refrigerators working with the regularity of 
steam engines, and continuously converting the mother- 
waters in basins of several acres of surface into a snow 
of sulphate of soda on the one hand and chloride of 
potassium on the other. Here is an unlimited source 
of this salt which will render the greatest services to 
agriculture, when its conversion into carbonate shall be 
arrived at, for, as I have before stated, it cannot be 
employed in its natural state. 

I was enthuiastic with this magnificent manufacture, 
but I have recently learned of the existence of another, 
which appears to me to be still more important. 



83 



Felspathic rocks, which in many countries exist in 
inexhaustible masses, all contain potassa. Orthose con- 
tains as much as 14 per 100. This potassa, engaged 
in insoluble combinations, is completely inert • it be- 
comes accessible to vegetation only after the disaggre- 
gation and decomposition of the rocks of which it forms 
a part. Now these rocks decompose only with extreme 
slowness under the influence of atmospheric agents ; 
and to estimate the effect of this decomposition, we 
must reckon time by geological periods. 

To separate, by rapid and economical means, the 
potassa contained in feldspars, has for a long time been 
one of the most exciting problems of manufacturing 
chemistry. Many solutions have been proposed, but 
none of them have been successful in furnishing potassa 
really cheap. Messrs. Ward and Wynants, of Brussels, 
have solved this difficulty. They attack the feldspars 
by treating them with carbonate of lime and fluoride 
of calcium. The mass is next treated with water, which 
extracts the whole of the potassa in the state of carbon- 
ate. This reaction demands only a moderate tempera- 
ture, and leaves a useful residue ; it is therefore in 
excellent practical condition. The inventors are striv- 
ing to perfect the manufacture, and as the success of 
their enterprise will be a great boon to agriculture, we 
will conclude, gentlemen, by wishing them success. 



ANALYSIS. 



SUMMARY OF THE FOREGOING PROPOSITIONS. — COMPARISON OF 
THE NEW SYSTEM WITH PAST TRADITIONS AND PRACTICE. — THE 
dunghill the manure par excellence. —ANALYSIS OF ITS CHEM- 
ICAL CONSTITUENTS PROVES THAT IT CONTAINS THE FOUR ESSEN- 
TIAL FERTILIZING AGENTS: PHOSPHORIC ACID, LIME, POTASSA, 
AND NITROGENOUS MATTER. — AN EXACT BALANCE WITH REGARD 
TO THESE FOUR AGENTS EXISTS AMONG ALL THE SYSTEMS OF 
CULTIVATION, i. e. BETWEEN THE QUANTITIES SUPPLIED BY THE 
MANURE AND THAT CARRIED AWAY IN THE CROPS. — RESULTS OP 
THE TRIENNIAL ROTATION OF CROPS.— RESULTS OF THE FIVE 
YEARS' SYSTEM. — MEAN ANNUAL RETURN OF THE TWO SYSTEMS.— 
RESULTS OF VARIOUS CULTIVATIONS. — BEETROOT.— COLZA. — AD- 
VANTAGES OF THE NEW SYSTEM; MAINTAINS THE FERTILITY OF 
THE SOIL UNIMPAIRED, WHATEVER CROPS ARE CONTINUOUSLY 
GROWN, WITHOUT ROTATION. — COMPARISON OF THE QUANTITIES 
OF THE FOUR FERTILIZING AGENTS CONTAINED IN VARIOUS CROPS 
AND IN THE COMPLETE MANURE. — POWER OF PRODUCTION OF THE 
OLD PROCESSES OF CULTIVATION, COMPARED WITH THOSE OF 
THE NEW SYSTEM.— LAW WHICH REGULATES THE NEW SYSTEM, 
WHICH THROWS DOWN THE BARRIERS THAT HAVE HITHERTO 
LIMITED PRODUCTION. —ESTIMATE OF THE RESULTS OF ITS ADOP- 
TION IN FRANCE. — CONCLUSION. — RESULTS OF THE HARVEST OF 
1864, ON THE NEW SYSTEM. 

85 



LECTURE SIXTH. 



All that I have stated to you previously may be sum- 
med up in the two following propositions : — 

1st. — There exists four regulating agents par excel- 
lence in the production of vegetables : — nitro- 
genous matter, phosphate of lime, potassa and 
lime. 
2nd. — To preserve to the earth its fertility, we must 
supply it periodically with these four substances 
in quantities equal to those removed by the 
crops. 
Such, in their greatest simplicity, are the conclusions 
to which we have been unavoidably led by the discus- 
sion of the scientific experiments upon vegetation. Let 
us now examine to what point these results agree with 
the results of practice, and the traditions of the past. 

It is an admitted law in agriculture, that the soil will 
not yield crops without manure, and the manure par 
excellence, which practice has realized, is the farm dung- 
hill : — a collection of all the residues of the harvest, a 
true caput mortuum of agricultural operations. 

I do not know what the composition of the dung-hill 



87 



is, although I do not hesitate to assert that it includes 
the four agents of vegetable production : for, without 
their presence, its good effect would be incomprehen- 
sible. Here is its analysis. 



COMPOSITION OF 


THE DRY MANURE. 








Imperial Farm 


Farm at 






at Vincennes. Bochelbronn. 




' Carbon. . . 




[59.65 


35.5 


1 






Organic 
Elements. 


Hydrogen. 
Oxygen . . 




4.2 

25.8 






65.50 




, Nitrogen. 




2.08 






2.00 




' Phosphoric Acid.. . . 


0.88 






1.00 




Sulphuric 


Acid 


traces 






0.65 




Carbonic . 
Chlorine.. 
Ammonia 
Lime 


A.cid 


0.94 






0.66 






0.70 


20 


Mineral 


and Oxide of Iron 0.68 

, K.9S 


2.03 
2.81 
1.20 


Elements. 


Magnesia. 




0.32 




Potassa.. . 




. 2.46 ) 










Soda 




traces J 


2.60 




Soluble Si 
■ Sand 


lica 


1.41 ) 












25.66 i 


22.13 














100.09 


100.78 








(G. Ville.) 


(Boussingault.) 



Thus we find in the manure, the use of which is con- 
secrated by time, phosphoric acid, lime, potassa, and 
nitrogenous matter, the same substances which our re- 
searches have pointed out to us as being the starting 
point of all production. 



88 



Assuredly this coincidence is not the effect of chance. 
Our first proposition is then found to be fully verified. 
Let us see if it is the same with the second. To that 
end it will suffice to pass in review the system of cul- 
tivation most generally pursued, and to show that an 
exact balance, with regard to the four agents, exists 
among them all, between the quantity brought by ma- 
nure, and that carried off by the crops. Upon this 
second point the demonstration will be as conclusive as 
upon the first. 

The most ancient system of cultivation, which neces- 
sity devised, and practice recognized for maintaining 
the fertility of the soil, is that which is still employed 
in many countries under the name of triennial rotation. 
Every three years the soil receives eight tons of ma- 
nure per acre ) it lies one year in fallow, and after- 
wards produces two crops of wheat. 



89 



Here are the results of this system : — 



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90 



You see that the balance is strikingly exact with re- 
gard to the nitrogen and the phosphoric acid ; as to the 
potassa and lime, it accumulates for the benefit of the 
soil. 

There is, then, nothing surprising in the fact of this 
system maintaining the fertility of the soil, as nothing 
is lost : but upon what conditions ? 

To obtain these eight tons of manure required every 
three years, we must raise cattle : to feed them requires 
pasture : and to maintain this pasture requires irriga- 
tion. It is then, in fact, to the water of irrigations that 
the triennial rotation derives the four agents which it 
exports under the form of grain, and to obtain them 
it is obliged to devote one-third of the farm to pasture. 
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nial system. 

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clover and similar plants into the rotation. In this 
manner the rotation is extended to five years. The 
crops of clover and roots have nourished the cattle, and 
the system has sufficed for itself. Here, also, are the 
data to which it gives rise. 





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92 



The triennial system accumulates important quanti- 
ties of alkalies and lime in the soil as pure loss. But 
through the clover and the roots, which have a marked 
preference for these elements, they are in great mea- 
sure turned to account. But the greatest advantage of 
the five year rotation consists in its influence with re- 
gard to nitrogen. You see that the cost of this ele- 
ment was repaid in benefiting the crops, and if you seek 
the plant to which this benefit is due, you will find that 
it is the clover, to the vegetable that forms part of the 
system. 

You will remember that, while the cereals draw the 
greater part of their nitrogen from the soil, vegetables, 
on the contrary, obtain it from the atmosphere. Thus 
you perceive, that the crop of wheat which follows the 
clover is more abundant, and contains more nitrogen, 
than that which preceded it — which proves that the 
clover has not impoverished the sail of that element. 

The five years' rotation, therefore, realizes the con- 
tinuous culture. It has two important advantages over 
the preceding. 1. It derives a portion of the nitrogen 
of the crops from the atmosphere. 2. It turns to ac- 
count the excess of potassa and lime brought by the 
manure. And the crops are also more abundant, as is 
shown by the following table. 



93 



MEAN ANNUAL RETURN OF THE TWO SYSTEMS. 

Triennial. Quinquennial, 
lbs. lbs. 

Weight of dried crop, per acre 2455 3131 

Nitrogen contained in this crop 25 44 

With the five years' rotation, agriculture has been 
brought to substitute the exportation of meat for that 
of the cereals, and it has derived decided advantages 
from the substitution ; for the sale of the cereals causes 
a loss of potassa, phosphoric acid and nitrogen to the 
farms, which cannot be compensated for except by a 
supply of manure, or by irrigation. If, on the contra- 
ry, the crops are consumed on the farm by the animals, 
we find in their excrements almost the whole of the 
phosphoric acid and potash contained in their food. 
The quantities that fix themselves in their tissues and 
bony structure, constitutes but a small loss. As to the 
nitrogen, their respiration rejects about a third of it 
into the atmosphere, in the gaseous state ; the other 
two-thirds return to the soil in the manure. This 
would be a loss, inevitably impoverishing the farm, 
without the clover, which derives an equivalent quan- 
tity from the atmosphere. 

It follows, from this, that the raising of cattle results 
in preserving to the soil almost the whole of the four 
agents which assures its fertility, and of procuring ben- 
efits in money without sensibly impoverishing the 
farm. 



94 



You see that the five years' system no more opposes 
our conclusions than the triennial j they receive, on 
the contrary, an unexpected light, and consequently af- 
ford them a striking confirmation. 

But, you will ask, is this the best practice devised ? 
No, Gentlemen. There exists a cultivation which re- 
alizes considerable profits, and which, when well carried 
out, causes almost no loss at all to the soil — that is 
the manufacturing cultivation of beetroot. In this 
case the exports are sugar or alcohol, substances ex- 
clusively composed of carbon, oxygen, and hydrogen, 
derived from water and the atmosphere. The ex- 
pressed pulp serves to nourish the cattle, and almost 
the whole of the useful elements are returned to the 
soil, especially if care be taken to mix the residue of 
distillation with the manure, instead of extracting the 
potash. 

Such are the systems of agriculture, developed dur- 
ing ages of groupings, true arc of promise to agricul- 
ture, in which it had been rash to make the least at- 
tack. Now we see them brought to rational and posi- 
tive notions, and science, which has learned to unveil 
the mysteries of their success, will learn also to give 
them the last improvement of which they are suscepti- 
ble. Without quitting the ways of the past, it will 
point out a simpler and more perfect method, which 
will be the ideal realization of the principle to which 
practical agriculture has always instinctively endeav- 
ored to conform itself, and constantly approached, and 
which we can now formularize in few words. 



95 



Cultivate the soil, and realize its profits, without 
impoverishing it of the four agents which assure its 
fertility. 

In all the systems I have described, and even in the 
case of beetroot, the farm always loses the nitrogen 
which the animal dissipates in the elementary state, 
and the universal salts contained in the cattle exported. 

A system, from which these losses were banished, 
would be the crown of the old method. It is colza 
that furnishes it. 

Its seed contains oil, a product of great value, and, 
like sugar, composed of carbon, oxygen, and hydrogen. 
Imagine an estate exclusively devoted to the cultiva- 
tion of colza, and that an oil-mill is attached to it. 
The oil will be exported, and will yield returns in 
cash ; all the rest, stems and oil-cake, will be returned 
to the soil without even passing through the medium 
of cattle. To this end we must add to the extraction 
of soil by pressure, a supplementary extraction by 
solution. The oil-cake, upon being removed from the 
hydraulic press, still contains 14 per 100 of oil, and 
sells at 6s. Gd. the cwt. The oil alone which they 
contain possesses this value. The substance of the 
oil-cake is thus gratuitously lost to the farm. When 
the oil is extracted by an appropriate solvent, sulphide 
of carbon, for example, in closed apparatus, constructed 
in such manner that a small quantity of this liquid 
put in circulation may exhaust considerable masses of 
it, there will remain a dry and pulverulent oil-cake, 



96 



containing all the products extracted from the soil. 
They are mixed with the stems on the dungbeap, and 
water is added. Putrefaction soon sets in, and we ob- 
tain an excellent manure, which restores to the soil 
the whole of the elements which the crops had re- 
moved from it, and which received the benefit of all 
the nitrogen derived from the atmosphere. 

After having discovered by what series of compen- 
sations the practice of the past arrived at conforming 
to the superior laws of vegetable production — laws of 
which it knew nothing — science may even imagine a 
simpler system, from which animals, and the loss they 
cause, are excluded, and which, yielding important 
profits, while enriching the soil, presents itself as the 
last degree of perfection to which it is possible to 
arrive by the methods of the past. 

But the fertility of the principles I have explained 
do not stop there. We must now abolish the practices 
pointed out to you, and replace them by a simpler agri- 
culture, more mistress of itself, and more remunerative. 
Instead of compelling ourselves by infinite cares and 
precautions to maintain the fertility of the soil, we re- 
constitute it, in every respect, by means of the four 
agents which I have pointed out, and which we can 
derive from the great stores of nature. Then no rota- 
tion of crops is necessary, no cattle, no particular choice 
in cultivation. We produce at will, sugar or oil, meat 
or bread, according as it best serves our interest. We 
export without the least fear the whole of the products 



97 



of our fields, if we see our advantage in so doing. 
We cultivate the same plant upon the same soil, in- 
definitely, if we find a good market for the produce. 
In a word, the soil is to us in future merely a medium 
of production, in which we convert at pleasure the four 
agents in the formation of vegetables into this or that 
crop which it suits us to produce. We are restrained 
only by a single necessity : to maintain at the disposal 
of our crops these four elements in sufficient propor- 
tion, so that they may always obtain the quantity their 
organization demands. 

Let us see to what point this condition is fulfilled 
in our new methods. To this end, it will be sufficient 
to compare the composition of the crops obtained 
from the farm at Vincennes with that of a complete 



98 













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You perceive, Gentlemen, that our new system satis- 
fies the law of equilibrium as well as the systems of 
the past : only, we hold the balance in our hands, and 
in proportion as one of the scales tends to rise, we 
restore the equilibrium by loading the other with an 
equal weight. 



99 



In the old systems, in which we maintained the 
equilibrium blindly, it frequently happened that one 
of the useful elements partially failed, and that the 
crops were also deficient. With the new processes, the 
plants, finding in abundance all they require, always 
attain their maximum of possible development; the 
crops are also much more abundant, as may be seen by 
the following table. 

POWER OF THE PRODUCTION OF THE OLD PRO- 
CESSES OF CULTIVATION COMPARED WITH 
THOSE OF THE NEW SYSTEM. 

Yield per Acre. 

Old Processes. New Processes. 

( Straw. ..8.250) Straw 15 . 270 ) 

Wheats > 11.889 > 23.520 



! 



( Grain. . . 3 . 639 ) Grain 8.250 j 

i Straw. . . 5 . 414 ) Straw 10 . 014 ) 

Peas \ > 7.610 > 12.863 

(Grain... 2. 196) Grain 2.849) 

Beetroot Roots 6.978 Roots 20.110 

But it is not sufficient to indicate the means of 
producing abundant crops j we must also show the 
method to be followed in order to obtain them econo- 
mically. 

The application of complete manures creates fertility 
everywhere ; but it is not everywhere nor always neces- 
sary to have recourse to so expensive a compound. 

When we suppress any of the constituent agents — 
the nitrogenous matters, for example — the yield of 



100 



wheat immediately undergoes a considerable reduction, 
but that of peas and vegetables is not affected by it. 
Suppress, on the contrary, the potassa : then the yield 
of the vegetables suffers most. For farnips, parsnips, 
and roots generally, it is the suppression of phosphate 
of lime which produces the worst effects. These results 
lead us to admit that among the four agents in each 
kind of crop there is one which exercises a more par- 
ticular influence upon the yield. 

We therefore formularize the following law, which 
will regulate the new agricultural practice. 

Although the presence of the four agents of fertility 
in the soil is necessary and indispensable for all plants, 
the exigencies of various cultivations are not the same 
with regard to the quantities of each of these agents — 
or in other words, each crop has its leading one. 

Thus, nitrogenous matter is the dominant agent for 
wheat and beetroots, potash for vegetables,, phosphate 
of lime for roots, &c. 

Suppose we undertake the cultivation of a piece of 
poor land. We begin by giving it the complete ma- 
nure, in order to create a sufficient provision of the four 
agents of fertility. We raise one or two crops of cereals 
upon this manure : then we continue the culture by 
giving to the soil, each year, the dominant element of 
the crop we propose to raise. 

If we adopt a rotation of four years with such crops 
that, at the end, has received the four agents, we can 
continue thus indefinitely without ever requiring the 



101 



complete manure. The same system is applicable to a 
fertile soil ; only we may dispense with the first dose 
of complete manure, and commence immediately by the 
dominant element of the first crop we desire to raise. 

If, on the contrary, it be desired to continue the 
same crop indefinitely, we content ourselves generally 
with the employment of its dominant ; but taking care 
to resume the application of the complete manure, imme- 
diately that a slight reduction in the weight of the 
crop points out the necessity for so doing. 

By these simple combinations we are in possession 
of a new agriculture, immeasurably more powerful than 
its predecessor. 

Formerly, the total matter placed by nature at the 
disposal of organized beings like ourselves, had its 
limits. All that the systems in vogue could do, was to 
maintain it ; but none succeeded in increasing it. 

With regard to the problems of life and population, 
human power encounters an impassable limit. The 
new processes of cultivation will have the effect of sup- 
pressing this barrier. Under their influences matters 
at present without value, which scarcely serve as mate- 
rials of construction, and of which nature possesses 
inexhaustible stores, can be converted into vegetable 
products : — forage to nourish the animals upon which 
we feed ; and cereals, to produce bread, the most valu- 
able of our resources. From this, the great stream of 
organized matter which sustains every existence will 
be increased with new waves, and the level of life will 



102 



continue unceasingly to rise to the surface of the 
globe. 

But, Gentlemen, beneath these great results which 
present themselves to the philosophic mind, there are 
others, more immediate, more practical — if I may so 
express myself, — which the system I strive to make 
prevail also carries on its flanks. 

Since the Revolution of 1789, the territory of France 
has continually been parcelled out in smaller portions. 
This fact has often been proclaimed ; but the evil still 
continues unremedied. 

According to official returns, the superficial area of 
France is now divided as follows : — 



Nature of the Property. 


Mean 
Extent. 


Surface 
occupied. 


Corresponding 
Population. 




Acres. 


Acres. 




Large Estates 


415 


43,320,000 


1,000,000 


Medium Estates. . . . 


87.50 


19,250,000 


1,000,000 


Small Estates 


35 


16,800,000 


2,400,000 


Very small Estates. . 
Totals 


8.62 


36,130,000 


19,500,000 


115,500,000 


24,000,000 



Of the one hundred and fifteen millions of acres of 
cultivated land, there are thirty-six millions possessed 
by proprietors whose estates do not exceed eight and a 
half acres in extent. What kind of agricultural sys- 



103 



tern can a man pursue who possesses only eight acres 
for every thing, and who requires as much for the sup- 
port of his family ? How, and with what, will he obtain 
manure ? He can have neither meadows nor cattle. 
He must necessarily farm badly; his land is fatally 
condemned to sterility, and himself to poverty. 

To combine the agents of fertility which have re- 
posed in geological strata since the foundations of the 
earth were laid, to place them at the disposal of the 
small farmer, will be to give fertility to fifty millions 
of acres devoted to the small and minimum cultivation, 
and create prosperity among twenty out of the twenty- 
four millions occupied in agricultural industry. 

Now I ask you, Gentlemen, if these views are not 
superior to the finest dreams of charity and philan- 
thropy ? Would they not also, if they were merely in 
the condition of scientific conceptions, suftice to excite 
our zeal ? But experience has returned its verdict. 
The crops you have before your eyes prove that with a 
manure, averaging in cost about five pounds a year, it 
is possible to obtain abundant harvests. Reduce, if 
you will, the excess of production, per acre, to a ton, 
which is here raised above three tons ; and applying 
this data to the fifty millions of badly cultivated acres, 
and see to what financial results we shall be inevit- 
ably led. 

The first movement in this direction will create a 
demand for fertilizing materials to the extent of some 
millions. What an impulse this must give to com- 
merce ! 



104 



Next to obtain twenty millions of tons more wheat 
than French agriculture supplies at the present time, 
and consequently an increase of wealth of about five 
millions sterling. What a guaranty against famine ! 

What is required to accomplish such a revolution ? 
We must apply the principles I have explained to you, 
and generalize them. In the second place, commerce 
must place the agents of fertility under the protection of 
new institutions of credit. They must be so conceived 
that the advances for the necessary manures may be 
made to the small farmer, to be repaid out of the ex- 
cess of crops derived from the fertilizers. 

The solution of this problem connects itself in a sin- 
gular manner with social and political destinies. Every- 
where the approach of democracy manifests itself. Is 
this a good ? Is it an evil ? I am not competent to de- 
cide the question : but it is very certain that at the 
present time the greater part of agricultural population 
deserts the country to seek an easier condition of life in 
the cities. 

This immense class, second only to the working pop- 
ulation of the cities, represents, in a high degree, the 
true public spirit. 

To change its economic situation, to put it into a 
condition of more intensive cultivation, notwithstanding 
the exigences of the scale upon which it operates, is to 
attach it tp the soil by its own interests. By this 
means a large conservative party may be created, with- 
out which a democracy based upon commerce will grow 



105 



up, leading only to a crisis analagous to that which now 
presents so deplorable a spectacle in America. 

England has avoided this danger at the price of an 
enlightened and patriotic aristocracy, but whose exist- 
ence perpetuates an inequality in human destinies 
which conscience repudiates and the laws of humanity 
condemn. Neither England nor America, therefore, 
have solved the problem of a powerful, wise, and just 
democracy. 

To me, it seems that our beautiful country is pre- 
destined to give this great example to the rest of the 
world, and I have the firm hope that the principles I 
have placed before you, in the course of these lectures, 
will serve as the starting point to the realization of this 
inestimable result. 



APPENDIX, 



EXPERIMENTAL FARM AT VINCENNES. 

HARVEST OF 1864. 

On the 31st of July, M. George Ville reaped and 
thrashed his crops in presence of a large concourse of 
agriculturists. The results were as follows: — 

Wheat: — Third Crop from the same land without fresh manure 
since the first application. 

Crop per Acre. Without Manure. With Complete Manure. 

Straw 704 lbs 5.913 lbs. 

Grain 193 "..... 2.464 " 

Total . . . 0.897 lbs 8.377 lbs. 

Wheat : — Fourth Crop without Fresh Manure since the first. 
Crop per Acre. Without Manure. With Complete Manure. 

Straw 1.074 lbs 4.629 lbs. 

Grain 316 " 1.760 " 

Total . . . 1.390 lbs 6.389 lbs. 

Colza : — Coming after two Crops of Barley without fresh Manure. 
Crop per Acre. Without Manure. With Complete Manure. 

Straw and Silicates . 5.632 lbs 7.700 lbs. 

Grain 1.320 " 2.410 " 

Total . . . 6.952 lbs 10.110 lbs. 



107 
CROPS OF 1864. — BEETROOT. 

On the 30th of October the crop of Beetroots was 
publicly got in. The results obtained were as fol- 
low: — 



.. Soil without Manure. 




Crop per Acre. 




Leaves 


6.204 lbs. 




. 16.544 " 






Total .... 


. 22.748 lbs. 



This piece of land, put under cultivation in 1861, had previously 
yielded two crops. 

In 1861. In 1S62. 

Crop per Acre. 

Leaves .... 14.696 lbs Leaves .... 7.040 lbs. 

Roots .... 44.616 " Roots .... 12.056 " 



59.312 lbs. 19.096 lbs. 

In 1863 the crops were devoured by the white worm, 
consequently there was no return, and this year's crop 
was a little increased by the preceding year being 
fallow : — 

2. Soil with Complete Manure. 

Crop per Acre. 

Leaves 6.618 lbs. 

Roots 24.990 " 

31.608 lbs. 

This piece of land, like the preceding, had furnished two previous 
crops since ir received any manure. 



108 



In 1861. In 1862. 

Crop per Acre. 

Leaves .... 14.344 lbs. Leaves .... 9.680 lbs. 

Boots .... 47.960 " Roots .... 21.820 " 



62.304 lbs. 31.500 lbs. 

3. Land with Complete Manure, but which has received acid 
phosphate of lime instead of ordinary phosphate. 

Leaves 7.700 lbs. 

Roots 30.624 " 



38.324 lbs. 



This piece of land had also yielded two crops previous, since it had 
received any manure. 

In 1861. In 1862. 

Crop per Acre. 

Leaves .... 15.488 lbs. Leaves .... 11.000 lbs. 

Roots .... 78.786 " Roots .... 33.968 " 



94.275 lbs. 44.968 lbs. 

4. Land with Complete Manure. — Crop of Beetroot coining 
after three fine crops of Wheat without fresh manure. 

Crop per Acre. 

Leaves 7.304 lbs. 

Roots 36.826 " 

44.130 lbs. 






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